CN113448197A

CN113448197A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Info

Publication number: CN113448197A
Application number: CN202010934551.0A
Authority: CN
Inventors: 星崎武敏; 渡边裕祐; 松木敬子; 上条由纪子; 新宫剑太; 铃木友子; 山田涉
Original assignee: Fujifilm Business Innovation Corp
Current assignee: Fujifilm Business Innovation Corp
Priority date: 2020-03-25
Filing date: 2020-09-08
Publication date: 2021-09-28
Also published as: US20210311404A1; US11209740B2

Abstract

The invention relates to an electrophotographic photoreceptor, a process cartridge and an image forming apparatus. An electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, (1) the fluorine atom concentration at the surface of the outermost surface layer being 1.5 times or more and 5.0 times or less the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or (2) the ratio (N2/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in a first region from the surface to 1/2 of the layer thickness of the outermost surface layer to the number density (N2) of the aggregates of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to the bottom surface of the outermost surface layer is less than 0.95, and the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in the first region to the area ratio (S2) of the fluorine-containing resin particles in the second region is within the range of 1 + -0.1.

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

The invention relates to an electrophotographic photoreceptor, a process cartridge and an image forming apparatus.

Background

Patent document 1 proposes "a photoreceptor containing fluororesin fine particles in an outermost surface layer of the photoreceptor, the photoreceptor having an outermost surface whose fluorine atom saturation amount is 20 to 60 atm%, and the fluorine atom saturation amount is increased and saturated by repeated use in an electrophotographic apparatus. ".

Patent document 2 discloses "a paste composition for electrodes, which contains metal particles containing copper as a main component, a flux, glass particles, a solvent, and a resin".

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-266036

Patent document 2: japanese patent laid-open publication No. 2011-090214

Disclosure of Invention

Problems to be solved by the invention

The invention provides an electrophotographic photoreceptor, which can inhibit the generation of image defects compared with the following cases: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, an outermost surface layer containing fluorine-containing resin particles, wherein a fluorine atom concentration at a surface of the outermost surface layer is less than 1.5 times or more than 5.0 times a fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; alternatively, an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, and the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in a first region from the surface of the outermost surface layer to 1/2 of the layer thickness to the area ratio (S2) of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to the bottom surface of the outermost surface layer is in the range of 1 + -0.1, wherein the ratio (N2/N1) between the number density (N1) of the fluorine-containing resin particles in a first region from the surface to 1/2, which is the layer thickness, of the outermost surface layer and the number density (N2) of the fluorine-containing resin particles in a second region from 1/2, which is the film thickness, of the outermost surface layer to the bottom surface of the outermost surface layer is 0.95 or more.

Means for solving the problems

The above problems are solved by the following means <1> to <17 >. That is to say that the first and second electrodes,

<1> an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer,

the outermost surface layer contains fluorine-containing resin particles,

the fluorine atom concentration at the surface of the outermost surface layer is 1.5 times or more and 5.0 times or less the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or the ratio (N2/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in a first region from the surface to 1/2 where the layer thickness is equal to or less than 0.95 to the number density (N2) of the aggregates of the fluorine-containing resin particles in a second region from 1/2 where the film thickness is equal to or less than 0.95,

the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in a first region from the surface to 1/2, which is the layer thickness, of the outermost surface layer to the area ratio (S2) of the fluorine-containing resin particles in a second region from 1/2, which is the film thickness, to the bottom surface of the outermost surface layer is within the range of 1 + -0.1.

<2> the electrophotographic photoreceptor as stated in <1>, wherein the surface of the outermost surface layer has an area occupied by the fluorine-containing resin particles of 0.33% to 1.1%.

<3> the electrophotographic photoreceptor according to <2>, wherein the surface of the outermost surface layer has an area occupied by the fluorine-containing resin particles of 0.36% to 0.95%.

<4> the electrophotographic photoreceptor as stated in any one of above <1> to <3>, wherein the photosensitive layer has a charge generation layer and a charge transport layer,

the outermost surface layer is the charge transport layer,

the concentration of the charge transport material at the surface of the charge transport layer is 0.4 to 0.6 times the concentration of the charge transport material at the center of the thickness of the charge transport layer.

<5> the electrophotographic photoreceptor as stated in <4>, wherein a concentration of the charge transport material at a surface of the charge transport layer is 0.45 times or more and 0.56 times or less a concentration of the charge transport material at a center of a thickness of the charge transport layer.

<6> the electrophotographic photoreceptor <1>, wherein the ratio (N2/N1) is 0.1 to 0.8.

<7> the electrophotographic photoreceptor according to <1> or <6>, wherein a ratio (N3/N1) between a number density (N1) of the fluorine-containing resin particles in a first region from a surface of the outermost surface layer to 1/2 of a layer thickness and a number density (N3) of the fluorine-containing resin particles in a third region from 9/10 of the layer thickness from the surface of the outermost surface layer to a bottom surface of the outermost surface layer is 0.9 or less.

<8> the electrophotographic photoreceptor <7>, wherein the ratio (N3/N1) is 0.7 or less.

<9> the electrophotographic photoreceptor according to any one of <1> and <6> to <8>, wherein a ratio (D2/D1) between an average diameter (D1) of the aggregate of the fluorine-containing resin particles in a first region from a surface of the outermost surface layer to 1/2 of a layer thickness and an average diameter (D2) of the aggregate of the fluorine-containing resin particles in a second region from 1/2 of the film thickness to a bottom surface of the outermost surface layer is 2 or more.

<10> the electrophotographic photoreceptor <9>, wherein the ratio (D2/D1) is 3 or more and 30 or less.

<11>Such as<1>、<6>～<10>The electrophotographic photoreceptor according to any one of the above items, wherein the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1/2, which is the layer thickness of the outermost surface layer, is 5 particles/100 μm ²50 pieces/100 mu m²The following.

<12>Such as<1>、<6>～<11>The electrophotographic photoreceptor according to any one of the above, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 per 10 of the fluorine-containing resin particles⁶The number of carbon atoms is 0 to 30, and the amount of the basic compound in the fluorine-containing resin particles is 0ppm to 3 ppm.

<13>Such as<12>The electrophotographic photoreceptor, wherein the number of carboxyl groups is 10 per unit⁶The number of carbon atoms is 0 to 20, and the amount of the basic compound is 0ppm to 3 ppm.

<14> A process cartridge comprising the electrophotographic photoreceptor according to any one of <1> to <13>,

the image forming apparatus is configured to be attached to and detached from the image forming apparatus.

<15> a process cartridge comprising the electrophotographic photoreceptor according to any one of <1> to <5>, which is configured to be attached to and detached from an image forming apparatus,

the process cartridge includes a cleaning member configured to contact the electrophotographic photoreceptor to clean the electrophotographic photoreceptor,

the contact pressure of the cleaning member to the electrophotographic photoreceptor is 1.0g/mm or more and 4.0g/mm or less.

<16> an image forming apparatus, comprising:

the electrophotographic photoreceptor according to any one of <1> to <13 >;

a charging mechanism configured to charge a surface of the electrophotographic photoreceptor;

an electrostatic latent image forming mechanism configured to form an electrostatic latent image on the surface of the charged electrophotographic photoreceptor;

a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoconductor with a developer containing a toner to form a toner image; and

and a transfer mechanism configured to transfer the toner image onto a surface of a recording medium.

<17> an image forming apparatus, comprising:

the electrophotographic photoreceptor according to any one of <1> to <5 >;

a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoconductor with a developer containing a toner to form a toner image;

a transfer mechanism configured to transfer the toner image onto a surface of a recording medium; and

a cleaning mechanism configured to clean the surface of the electrophotographic photoreceptor by bringing a cleaning member into contact with the surface,

ADVANTAGEOUS EFFECTS OF INVENTION

According to the aspect of <1>, an electrophotographic photoreceptor capable of suppressing the occurrence of image defects can be obtained as compared with the case where: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, an outermost surface layer containing fluorine-containing resin particles, wherein a fluorine atom concentration at a surface of the outermost surface layer is less than 1.5 times or more than 5.0 times a fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; alternatively, an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, and the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in a first region from the surface of the outermost surface layer to 1/2 of the layer thickness to the area ratio (S2) of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to the bottom surface of the outermost surface layer is in the range of 1 + -0.1, wherein the ratio (N2/N1) between the number density (N1) of the fluorine-containing resin particles in a first region from the surface to 1/2, which is the layer thickness, of the outermost surface layer and the number density (N2) of the fluorine-containing resin particles in a second region from 1/2, which is the film thickness, of the outermost surface layer to the bottom surface of the outermost surface layer is 0.95 or more.

According to the embodiment <2> or <3>, compared with the case where the area occupied by the fluorine-containing resin particles is less than 0.36% or exceeds 0.95% on the surface of the outermost surface layer, the electrophotographic photoreceptor can be obtained which can suppress the generation of the streak-like image defect caused by rubbing the photoreceptor and the contact member thereof due to vibration and the residual potential.

According to the aspect of <4> or <5>, an electrophotographic photoreceptor capable of suppressing generation of a stripe-like image defect and a residual potential, which are caused by rubbing of the photoreceptor and a contact member thereof due to vibration, can be obtained as compared with the case where: an electrophotographic photoreceptor, wherein the photosensitive layer has a charge generation layer and a charge transport layer, and the outermost layer is the charge transport layer, wherein the concentration of the charge transport material at the surface of the charge transport layer is less than 0.45 times or more than 0.56 times the concentration of the charge transport material at the center of the thickness of the charge transport layer.

According to the aspect of <6>, an electrophotographic photoreceptor more excellent in both sensitivity and abrasion resistance can be provided as compared with the case where the above-mentioned ratio (N2/N1) is less than 0.1 or exceeds 0.8.

According to the embodiment of <7>, the electrophotographic photoreceptor having both excellent sensitivity and wear resistance can be provided as compared with the case where the ratio (N3/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface of the outermost surface layer to 1/2 where the layer thickness is from the surface to the bottom surface of the outermost surface layer to the number density (N3) of the aggregates of the fluorine-containing resin particles in the third region from 9/10 where the layer thickness is from the surface of the outermost surface layer to the bottom surface of the outermost surface layer exceeds 0.9. Further, an electrophotographic photoreceptor in which the generation of color dots due to the incorporation of needle-like foreign matter is further suppressed can be provided.

According to the aspect of <8>, an electrophotographic photoreceptor more excellent in both sensitivity and abrasion resistance can be provided as compared with the case where the above ratio (N3/N1) exceeds 0.7. Further, an electrophotographic photoreceptor in which the generation of color dots due to the incorporation of needle-like foreign matter is further suppressed can be provided.

According to the embodiment of <9>, the electrophotographic photoreceptor having both excellent sensitivity and wear resistance can be provided as compared with the case where the ratio (D2/D1) of the average diameter (D1) of the aggregate of the fluorine-containing resin particles in the first region from the surface of the outermost surface layer to 1/2 where the layer thickness is from 1/2 to the bottom surface of the outermost surface layer to the average diameter (D2) of the aggregate of the fluorine-containing resin particles in the second region from 1/2 of the film thickness is less than 2.

According to the aspect of <10>, an electrophotographic photoreceptor more excellent in both sensitivity and abrasion resistance can be provided as compared with the case where the above ratio (D2/D1) is less than 3 or exceeds 30.

According to<11>The number density (N1) of the aggregates with the fluorine-containing resin particles in the first region from the surface to 1/2 where the layer thickness is the layer thickness of the outermost surface layer is less than 5 particles/100 [ mu ] m²Or more than 50/100 μm²Can provide an electrophotographic photoreceptor more excellent in both sensitivity and wear resistance than in the case of (2).

According to<12>The amount of the carboxyl groups in the fluorine-containing resin particles is 10 times⁶The electron having a carbon number of more than 30 and an amount of the basic compound of 0ppm or more and 3ppm or less can be provided with excellent chargeabilityA photographic photoreceptor.

According to<13>The number of the carboxyl groups is 10⁶An electrophotographic photoreceptor having excellent chargeability can be provided as compared with the case where the number of carbon atoms is more than 20 and the amount of the basic compound is 0ppm or more and 3ppm or less.

According to the aspect of <14> or <16>, a process cartridge or an image forming apparatus capable of suppressing the occurrence of image defects can be obtained as compared with the case where: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, wherein an outermost surface layer contains fluorine-containing resin particles, and the fluorine atom concentration at the surface of the outermost surface layer is less than 1.5 times or more than 5.0 times the fluorine atom concentration at a depth of 1 [ mu ] m from the surface of the outermost surface layer; alternatively, an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, and the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in a first region from the surface of the outermost surface layer to 1/2 of the layer thickness to the area ratio (S2) of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to the bottom surface of the outermost surface layer is in the range of 1 + -0.1, wherein the ratio (N2/N1) between the number density (N1) of the fluorine-containing resin particles in a first region from the surface to 1/2, which is the layer thickness, of the outermost surface layer and the number density (N2) of the fluorine-containing resin particles in a second region from 1/2, which is the film thickness, of the outermost surface layer to the bottom surface of the outermost surface layer is 0.95 or more.

According to the aspect of <15> or <17>, a process cartridge or an image forming apparatus capable of suppressing the occurrence of image defects can be obtained as compared with the case where: a process cartridge or an image forming apparatus, comprising an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, and a cleaning member which is brought into contact with the electrophotographic photoreceptor to perform cleaning, wherein an outermost surface layer contains fluorine-containing resin particles, and a fluorine atom concentration at a surface of the outermost surface layer is 1.5 times or more and 5.0 times or less a fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer, and wherein a contact pressure of the cleaning member with respect to the electrophotographic photoreceptor is less than 1.0g/mm or more than 4.0 g/mm.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to embodiment 1.

Fig. 2 is a schematic configuration diagram showing an example of the image forming apparatus according to embodiments 1 and 2.

Fig. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to embodiments 1 and 2.

Fig. 4 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to embodiment 2.

Fig. 5 is a schematic sectional view showing another example of the layer configuration of the electrophotographic photoreceptor of embodiment 2.

Detailed Description

The following describes an embodiment as an example of the present invention. These descriptions and examples are intended to illustrate embodiments and not to limit the scope of the invention.

In the numerical ranges recited in the present specification in stages, the upper limit or the lower limit recited in one numerical range may be replaced with the upper limit or the lower limit recited in another numerical range in another stage. In addition, in the numerical ranges described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

Each component may comprise two or more corresponding substances.

In the case where the amount of each component in the composition is referred to, in the case where two or more species corresponding to each component are present in the composition, the total amount of the two or more species present in the composition is referred to unless otherwise specified.

EXAMPLE 1 embodiment

< electrophotographic photoreceptor >

The electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") of the present embodiment has a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer contains fluorine-containing resin particles.

And the fluorine atom concentration measured on the surface of the outermost surface layer is 1.5 times or more and 5.0 times or less the fluorine atom concentration measured at a depth of 1 μm from the surface of the outermost surface layer.

With the above configuration, the photoreceptor of the present embodiment can suppress the occurrence of a stripe-like image defect and the residual potential caused by the friction of the photoreceptor and the contact member thereof due to vibration. The reason is presumed as follows.

When the photoreceptor containing the fluorine-containing resin particles in the outermost surface layer is conveyed in a state of being incorporated in a process cartridge or an image forming apparatus, the photoreceptor and a member (cleaning member or the like) in contact with the photoreceptor rub against each other due to vibration during conveyance, and the rubbed portion of the photoreceptor may be frictionally charged to a positive electrode. Further, in a state where a portion of the surface of the photoreceptor that is triboelectrically charged to a positive electrode is present, if the photoreceptor is electrically charged at the time of image formation, stripe-like unevenness occurs in the surface potential of the photoreceptor, and a stripe-like image defect may occur in association therewith. Further, charges remain in the photosensitive layer of the photoreceptor, and a residual potential may occur.

On the other hand, in the photoreceptor containing the fluorine-containing resin particles in the outermost surface layer according to the present embodiment, the fluorine atom concentration measured on the surface of the outermost surface layer is 1.5 times or more and 5.0 times or less the fluorine atom concentration measured at a depth of 1 μm from the surface of the outermost surface layer. That is, the outermost surface layer contains a large amount of fluorine-containing resin particles. Since the fluorine-containing resin particles have a high negative polarity, even when the photoreceptor and a member in contact with the photoreceptor rub against each other due to vibration during conveyance, positive charges due to the rubbing can be easily eliminated, and the photoreceptor can be prevented from being triboelectrically charged to the positive electrode at the rubbed portion. Therefore, even if the photoreceptor is charged during image formation, the surface potential of the photoreceptor is less likely to be uneven in a stripe shape, and the residual potential is suppressed.

Thus, it is presumed that the photoreceptor of the present embodiment can suppress the generation of stripe-like image defects and residual potential caused by rubbing of the photoreceptor and the contact member due to vibration.

The photoreceptor of the present embodiment will be described in detail below.

Hereinafter, the electrophotographic photoreceptor of the present embodiment will be described with reference to the drawings.

The electrophotographic photoreceptor 7A shown in fig. 1 is, for example, a photoreceptor having a structure in which a primer layer 1, a charge generation layer 2 and a charge transport layer 3 are sequentially laminated on a conductive substrate 4. The charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer 5.

The electrophotographic photoreceptor 7A may have a layer structure in which the undercoat layer 1 is not provided.

The electrophotographic photoreceptor 7A may be a photoreceptor having a single-layer photosensitive layer in which the functions of the charge generation layer 2 and the charge transport layer 3 are integrated. In the case of a photoreceptor having a monolayer type photosensitive layer, the monolayer type photosensitive layer constitutes the outermost surface layer.

In addition, the electrophotographic photoreceptor 7A may be a photoreceptor having a surface protective layer on the charge transport layer 3 or on the single layer type photosensitive layer. In the case of a photoreceptor having a surface protective layer, the surface protective layer constitutes the outermost surface layer.

The respective layers of the electrophotographic photoreceptor of the present embodiment will be described in detail below. Note that the reference numerals are omitted for description.

(conductive substrate)

Examples of the conductive substrate include: comprising a metal sheet, a metal and a metal strip of metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloy (stainless steel, etc.). Examples of the conductive substrate include a conductive compound (e.g., a conductive polymer, indium oxide, etc.), a metal (e.g., aluminum, palladium, gold, etc.), or a paper, a resin film, a tape, and the like coated, deposited, or laminated with an alloy. Here, "electrically conductive" means having a volume resistivity of less than 10¹³Ωcm。

When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm or more and 0.5 μm or less for the purpose of suppressing interference fringes generated when the laser is irradiated. When non-interference light is used for the light source, it is not particularly necessary to prevent the interference fringes from being roughened, but since the roughening can suppress the occurrence of defects due to the surface irregularities of the conductive substrate, it is suitable for further lengthening the life of the light source.

Examples of the method of roughening include: wet honing by suspending an abrasive in water and blowing it to a conductive substrate; centerless grinding in which a conductive substrate is pressed against a rotating grinding wheel to continuously perform grinding; anodic oxidation treatment, and the like.

The method of roughening may be as follows: the surface of the conductive substrate is not roughened, but conductive or semiconductive powder is dispersed in a resin, a layer is formed on the surface of the conductive substrate, and the surface is roughened by particles dispersed in the layer.

The roughening treatment by anodic oxidation is a roughening treatment in which a conductive substrate made of metal (for example, aluminum) is anodized in an electrolyte solution using the conductive substrate as an anode to form an oxide film on the surface of the conductive substrate. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active in its original state, and is easily contaminated, and the resistance change due to the environment is also large. Therefore, the porous anodic oxide film is preferably subjected to the following sealing treatment: in pressurized steam or boiling water (metal salts such as nickel may be added), the micropores of the oxide film are blocked by volume expansion due to hydration reaction, and the oxide film becomes a more stable hydrated oxide.

The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the film thickness is within the above range, barrier properties tend to be exhibited against implantation, and increase in residual potential due to repeated use tends to be suppressed.

The conductive substrate may be subjected to treatment with an acidic treatment solution or boehmite treatment.

The treatment with the acidic treatment solution is performed, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment liquid may be, for example: phosphoric acid is in a range of 10 to 11 mass%, chromic acid is in a range of 3 to 5 mass%, hydrofluoric acid is in a range of 0.5 to 2 mass%, and the concentration of the whole acid may be in a range of 13.5 to 18 mass%. The treatment temperature is preferably 42 ℃ to 48 ℃ for example. The film thickness of the coating is preferably 0.3 μm to 15 μm.

The boehmite treatment is performed, for example, by immersing in pure water at 90 ℃ to 100 ℃ for 5 minutes to 60 minutes or by contacting with heated water vapor at 90 ℃ to 120 ℃ for 5 minutes to 60 minutes. The film thickness of the coating is preferably 0.1 μm or more and 5 μm or less. The anodic oxidation treatment may be further performed using an electrolyte solution having low solubility in the coating film, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

(undercoat layer)

The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

The inorganic particles include, for example, those having a powder resistance (volume resistivity) of 10²10 above omega cm¹¹Inorganic particles of not more than Ω cm.

Among these, as the inorganic particles having the above resistance value, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, zirconium oxide particles and the like can be used, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles based on the BET method may be, for example, 10m²More than g.

The volume average particle diameter of the inorganic particles may be, for example, 50nm to 2000nm (preferably 60nm to 1000 nm).

The content of the inorganic particles is, for example, preferably 10 mass% to 80 mass%, more preferably 40 mass% to 80 mass% with respect to the binder resin.

The inorganic particles may be subjected to a surface treatment. Among the inorganic particles, two or more kinds of inorganic particles having different surface treatments or inorganic particles having different particle diameters may be used in combination.

Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. Particularly preferred are silane coupling agents, and more preferred are silane coupling agents having an amino group.

Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, and N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane.

Two or more silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of the other silane coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane and the like, but is not limited thereto.

The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

The amount of the surface treatment agent to be treated is preferably 0.5 mass% or more and 10 mass% or less with respect to the inorganic particles, for example.

Here, the undercoat layer may contain an electron-accepting compound (acceptor compound) in addition to the inorganic particles, in view of high long-term stability of electrical characteristics and high carrier blocking property.

Examples of the electron-accepting compound include: quinone compounds such as chloranil and bromoaniline; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4, 7-trinitrofluorenone, 2,4,5, 7-tetranitro-9-fluorenone, etc.; oxadiazole-based compounds such as 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3, 4-oxadiazole, 2, 5-bis (4-naphthyl) -1,3, 4-oxadiazole, and 2, 5-bis (4-diethylaminophenyl) -1,3, 4-oxadiazole; a xanthone-based compound; a thiophene compound; and electron-transporting substances such as diphenoquinone compounds such as 3,3 ', 5, 5' -tetra-tert-butylbenzoquinone.

In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarine, anthropaucinol, purpurin and the like are preferable.

The electron accepting compound may be dispersed and contained in the undercoat layer together with the inorganic particles, or may be contained in a state of being attached to the surface of the inorganic particles.

Examples of the method for attaching the electron-accepting compound to the surface of the inorganic particle include a dry method and a wet method.

The dry method is, for example, the following method: the electron accepting compound is attached to the surface of the inorganic particles by directly dropping the electron accepting compound or dropping the electron accepting compound dissolved in the organic solvent while stirring the inorganic particles with a mixer having a large shearing force or the like, and spraying the mixture with dry air or nitrogen gas. The electron accepting compound is preferably dropped or sprayed at a temperature not higher than the boiling point of the solvent. After dropping or spraying the electron accepting compound, the mixture may be further calcined at 100 ℃ or higher. The baking is not particularly limited as long as the temperature and time are sufficient to obtain electrophotographic characteristics.

The wet method is, for example, the following method: the electron accepting compound is added to the solvent while dispersing the inorganic particles in the solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill or the like, and after stirring or dispersing, the solvent is removed to attach the electron accepting compound to the surface of the inorganic particles. The solvent removal method is, for example, filtration or distillation by distillation. After the solvent is removed, the mixture may be further calcined at 100 ℃ or higher. The baking is not particularly limited as long as the baking is at a temperature and for a time sufficient to obtain electrophotographic characteristics. In the wet method, the moisture contained in the inorganic particles may be removed before the electron-accepting compound is added, and examples thereof include a method of removing the moisture while stirring and heating the moisture in a solvent, and a method of removing the moisture by azeotropy with a solvent.

The electron accepting compound may be attached before or after the surface treatment with the surface treatment agent is performed on the inorganic particles, or the electron accepting compound may be attached and the surface treatment with the surface treatment agent may be performed simultaneously.

The content of the electron-accepting compound may be, for example, 0.01 to 20 mass%, preferably 0.01 to 10 mass%, relative to the inorganic particles.

Examples of the adhesive resin used for the undercoat layer include: known polymer compounds such as acetal resins (for example, polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone-modified alkyd resins, urea resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; a zirconium chelate compound; a titanium chelate compound; an aluminum chelate compound; a titanium alkoxide compound; an organic titanium compound; and known materials such as silane coupling agents.

Examples of the adhesive resin used for the undercoat layer include a charge-transporting resin having a charge-transporting group, a conductive resin (e.g., polyaniline), and the like.

Among these, as the adhesive resin used for the undercoat layer, a resin insoluble in the coating solvent of the upper layer is suitable, and particularly, a thermosetting resin such as a urea resin, a phenol-formaldehyde resin, a melamine resin, a urethane resin, an unsaturated polyester resin, an alkyd resin, an epoxy resin, or the like is suitable; a resin obtained by the reaction of at least one resin selected from the group consisting of a polyamide resin, a polyester resin, a polyether resin, a methacrylic resin, an acrylic resin, a polyvinyl alcohol resin, and a polyvinyl acetal resin with a curing agent.

When two or more of these binder resins are used in combination, the mixing ratio thereof is set as necessary.

The undercoat layer may contain various additives for improving electrical characteristics, environmental stability, and image quality.

Examples of the additive include known materials such as electron-transporting pigments of polycyclic fused system, azo system, etc., zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organotitanium compounds, silane coupling agents, etc. The silane coupling agent is used for the surface treatment of the inorganic particles as described above, but may be further added as an additive to the undercoat layer.

Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane and the like.

Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate.

Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octanedionate, titanium ammonium lactate, titanium ethyllactate, titanium triethanolamine, and titanium polyhydroxystearate.

Examples of the aluminum chelate compound include aluminum isopropoxide, aluminum monobutoxide diisopropoxide, aluminum butyrate, aluminum diisopropoxide diethylacetoacetate, and aluminum tris (ethylacetoacetate).

These additives may be used alone, or may be used in the form of a mixture or a polycondensate of two or more compounds.

The vickers hardness of the undercoat layer may be 35 or more.

As for the surface roughness (ten-point average roughness) of the undercoat layer, in order to suppress the moire image, it may be adjusted to 1/(4n) (n is the refractive index of the upper layer) to 1/2 of the wavelength λ of the exposure laser used.

In order to adjust the surface roughness, resin particles or the like may be added to the undercoat layer. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. In addition, in order to adjust the surface roughness, the surface of the undercoat layer may be polished. Examples of the polishing method include polishing, sand blasting, wet honing, and grinding.

The formation of the undercoat layer is not particularly limited, and a known formation method can be used, and for example, the formation can be performed by the following method: a coating film of a coating liquid for forming an undercoat layer, which is obtained by adding the above components to a solvent, is formed, and the coating film is dried and heated as necessary.

Examples of the solvent used for preparing the coating liquid for forming the undercoat layer include known organic solvents, for example, alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-alcohol solvents, ether solvents, ester solvents, and the like.

Specific examples of the solvent include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

Examples of the method for dispersing the inorganic particles in the preparation of the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

Examples of the method for applying the coating liquid for forming an undercoat layer on the conductive substrate include common methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The thickness of the undercoat layer is set, for example, preferably within a range of 15 μm or more, more preferably 20 μm or more and 50 μm or less.

(intermediate layer)

Although illustration is omitted, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone-modified alkyd resins, phenol-formaldehyde resins, and melamine resins.

The intermediate layer may be a layer comprising an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

These compounds for the intermediate layer may be used alone, or may be used in the form of a mixture of two or more compounds or a polycondensate.

Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

The formation of the intermediate layer is not particularly limited, and may be carried out by a known formation method, for example, by the following method: the intermediate layer is formed by forming a coating film of a coating liquid for forming an intermediate layer, which is obtained by adding the above components to a solvent, drying the coating film, and heating the coating film as necessary.

As a coating method for forming the intermediate layer, a common method such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a curtain coating method, or the like is used.

The thickness of the intermediate layer is preferably set to a range of 0.1 μm to 3 μm, for example. The intermediate layer may be used as an undercoat layer.

(Charge generation layer)

The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. In addition, the charge generation layer may be a vapor deposition layer of a charge generation material. The deposition layer of the charge generating material is suitable for a case where a non-interference Light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

Examples of the charge generating material include azo pigments such as bisazo and trisazo pigments; fused aromatic pigments such as dibromoanthanthrone (dibromoanthanthrone); perylene pigments; a pyrrolopyrrole pigment; phthalocyanine pigments; zinc oxide; trigonal selenium, and the like.

Among these, in order to cope with laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanines disclosed in, for example, Japanese patent application laid-open Nos. 5-263007 and 5-279591; chlorogallium phthalocyanine disclosed in Japanese patent laid-open No. 5-98181 or the like; dichlorotin phthalocyanines disclosed in, for example, Japanese patent application laid-open Nos. 5-140472 and 5-140473; titanyl phthalocyanines disclosed in Japanese patent laid-open No. 4-189873 and the like.

On the other hand, in order to cope with laser exposure in the near ultraviolet region, as the charge generating material, a fused aromatic pigment such as dibromoanthanthrone (dibromoanthanthrone); a thioindigo-based pigment; a porphyrazine compound; zinc oxide; trigonal selenium; and disazo pigments disclosed in Japanese patent laid-open Nos. 2004-78147 and 2005-181992.

The charge generating material can be used when a non-interference light source such as an LED having an emission center wavelength of 450nm to 780nm is used, or an organic EL image array, but from the viewpoint of resolution, when a photosensitive layer is used as a thin film of 20 μm or less, the electric field intensity in the photosensitive layer increases, and a decrease in charging due to charge injection from a substrate, that is, an image defect called a black spot, is easily generated. This is remarkable when a charge generating material which easily generates dark current in a p-type semiconductor, such as trigonal selenium or a phthalocyanine pigment, is used.

On the other hand, when an n-type semiconductor such as a fused aromatic pigment, a perylene pigment, an azo pigment or the like is used as a charge generating material, dark current is less likely to be generated, and image defects called black spots can be suppressed even when a thin film is formed. Examples of the n-type charge generating material include, but are not limited to, the compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of Japanese patent laid-open No. 2012-155282.

The n-type is determined by the polarity of a flowing photocurrent using a generally used time-flight method, and a type in which electrons flow as carriers more easily than holes is referred to as an n-type.

The adhesive resin used for the charge generating layer can be selected from a wide range of insulating resins, and the adhesive resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, and the like.

Examples of the binder resin include a polyvinyl butyral resin, a polyarylate resin (a polycondensate of a bisphenol and an aromatic 2-valent carboxylic acid, or the like), a polycarbonate resin, a polyester resin, a phenoxy resin, a vinyl chloride-vinyl acetate copolymer, a polyamide resin, an acrylic resin, a polyacrylamide resin, a polyvinyl pyridine resin, a cellulose resin, a urethane resin, an epoxy resin, casein, a polyvinyl alcohol resin, and a polyvinylpyrrolidone resin. Here, "insulating" means that the volume resistivity is 10¹³Omega cm or more.

These binder resins may be used singly or in combination of two or more.

The compounding ratio of the charge generating material to the binder resin is preferably 10: 1 to 1: 10, in the range of 10.

Other known additives may also be included in the charge generation layer.

The charge generation layer can be formed by a known method, for example, as follows: a charge generating layer is formed by forming a coating film of a charge generating layer forming coating liquid in which the above components are added to a solvent, drying the coating film, and heating the coating film as necessary. The charge generation layer may be formed by vapor deposition of a charge generation material. The vapor deposition formation of the charge generation layer is particularly suitable for the case where a fused aromatic pigment or a perylene pigment is used as the charge generation material.

Examples of the solvent used for preparing the coating liquid for forming a charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, toluene, and the like. These solvents may be used singly or in combination of two or more.

As a method of dispersing particles (for example, a charge generating material) in the charge generating layer forming coating liquid, for example, a media dispersing machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, etc.; stirring, ultrasonic disperser, roller mill, high-pressure homogenizer, etc. Examples of the high-pressure homogenizer include: a collision system for performing dispersion by causing the dispersion to undergo liquid-liquid collision or liquid-wall collision in a high-pressure state; a penetration system in which the dispersion is performed by penetrating through a fine flow path in a high-pressure state.

In this dispersion, it is effective that the average particle diameter of the charge generating material in the coating liquid for forming a charge generating layer is 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

Examples of the method for applying the coating liquid for forming a charge generation layer onto the undercoat layer (or onto the intermediate layer) include common methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The film thickness of the charge generation layer is set, for example, in the range of preferably 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

(Charge transport layer)

The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer comprising a polymeric charge transport material.

When the charge transport layer is the outermost surface layer, the charge transport layer contains fluorine-containing resin particles in addition to the binder resin and the charge transport material.

When another layer (for example, a surface protective layer or the like) is provided on the charge transport layer and the charge transport layer is not the outermost surface layer, the charge transport layer may contain at least a binder resin and a charge transport material, and may contain other additives as needed. The binder resin, the charge transport material, and other additives are the same as in the case where the charge transport layer is the outermost surface layer.

Adhesive resins

Examples of the binder resin used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinylcarbazole, polysilane, and the like. Among these, as the binder resin, a polycarbonate resin or a polyarylate resin is preferable. These adhesive resins may be used singly or in combination of two or more.

The mixing ratio of the charge transport material to the binder resin is preferably 10: 1 to 1: 5.

here, the content of the binder resin is, for example, preferably 10 mass% or more and 90 mass% or less, more preferably 30 mass% or more and 80 mass% or less, and further preferably 40 mass% or more and 70 mass% or less with respect to the total solid content of the photosensitive layer (charge transport layer).

Charge transport material

Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4, 7-trinitrofluorenone; a xanthone-based compound; a benzophenone-based compound; a cyanovinyl compound; electron-transporting compounds such as vinyl compounds. Examples of the charge transport material include hole transport compounds such as triarylamine compounds, biphenylamine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and the like. These charge transport materials may be used singly or in combination of two or more, but are not limited thereto.

As the charge transport material, triarylamine derivatives represented by the following general formula (a-1) and benzidine derivatives represented by the following general formula (a-2) are preferable in view of charge mobility.

In the general formula (a-1), Ar^T1、Ar^T2And Ar^T3Each independently represents a substituted or unsubstituted aryl group, -C₆H₄-C(R^T4)＝C(R^T5)(R^T6) or-C₆H₄-CH＝CH-CH＝C(R^T7)(R^T8)。R^T4、R^T5、R^T6、R^T7And R^T8Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Further, as the substituent of each group, there may be mentioned a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

In the general formula (a-2), R^T91And R^T92Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R^T101、R^T102、R^T111And R^T112Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C (R^T12)＝C(R^T13)(R^T14) or-CH-C (R)^T15)(R^T16)，R^T12、R^T13、R^T14、R^T15And R^T16Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

Among the triarylamine derivatives represented by the general formula (a-1) and the benzidine derivatives represented by the general formula (a-2), those having "-C" are preferable in view of charge mobility₆H₄-CH＝CH-CH＝C(R^T7)(R^T8) Triarylamine derivatives and compounds having "-CH-C (R)^T15)(R^T16) "a benzidine derivative.

As the polymer charge transport material, a known material having a charge transport property such as poly-N-vinylcarbazole or polysilane is used. In particular, the polyester-based polymeric charge transport materials disclosed in Japanese patent application laid-open Nos. 8-176293 and 8-208820 are particularly preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

The concentration of the charge transport material measured at the surface of the charge transport layer is preferably 0.4 to 0.6 times, more preferably 0.45 to 0.56 times, and still more preferably 0.45 to 0.54 times the concentration of the charge transport material measured at the center of the thickness of the charge transport layer.

When the ratio of the concentration of the charge transport material measured at the surface of the charge transport layer to the concentration of the charge transport material measured at the center of the thickness of the charge transport layer is within the above range, more charge transport material is contained in the center of the thickness of the charge transport layer than in the surface of the charge transport layer.

Since the charge transport material contains a hole transport material and the positive polarity of the hole transport material is high, if the charge transport material containing a hole transport material is contained in a large amount in the central portion of the thickness of the charge transport layer, triboelectric charging of the surface of the photoreceptor to the positive electrode due to friction can be further suppressed. Therefore, even if the photoreceptor is charged during image formation, the surface potential of the photoreceptor is less likely to be uneven in a stripe shape, and generation of stripe-shaped image defects and residual potential due to rubbing of the photoreceptor and a contact member thereof caused by vibration can be further suppressed.

A method of measuring the concentration ratio of the charge transport material in the charge transport layer will be described. The charge transport layer was cut off obliquely in the thickness direction, and the portion corresponding to the surface of the charge transport layer and the portion corresponding to the thickness center of the charge transport layer in the cross section were analyzed by microscopic infrared spectroscopic analysis. The peak of "C ═ C stretching vibration origin of the charge transport material" (1583.5 cm) was calculated from the measurement results of the surface of the charge transport layer and the thickness center of the charge transport layer^-1) Area ÷ peak derived from C ═ O of adhesive resin (1770 cm)^-1) Area ". The value obtained from the measurement result of the surface of the charge transport layer is divided by the value obtained from the measurement result at the center of the thickness of the charge transport layer, thereby calculating.

As a method of making the ratio of the concentration of the charge transport material measured at the surface of the charge transport layer to the concentration of the charge transport material measured at the center of the thickness of the charge transport layer within the above range, there is a method of forming a charge transport layer by quickly removing the solvent in the coating liquid for the charge transport layer after the coating liquid for the charge transport layer is applied.

Examples of a method for quickly removing the solvent in the coating liquid for a charge transport layer include: a method of heating a coating film surface formed from the coating liquid for a charge transport layer while blowing air; a method of reducing the thickness of the conductive substrate in order to facilitate heat transfer to the coating film formed from the coating liquid for a charge transport layer; and the like.

Fluorine-containing resin particles

Examples of the fluorine-containing resin particles include particles of a homopolymer of a fluoroolefin and particles of a copolymer of 1 or more species of fluoroolefin and a non-fluorine-based monomer (i.e., a monomer having no fluorine atom).

Examples of the fluoroolefin include a perhaloolefin such as Tetrafluoroethylene (TFE), perfluorovinyl ether, Hexafluoropropylene (HFP) or Chlorotrifluoroethylene (CTFE), a non-perfluoroolefin such as vinylidene fluoride (VdF), trifluoroethylene or vinyl fluoride. Among these, VdF, TFE, CTFE, HFP, and the like are preferable.

On the other hand, examples of the non-fluorine-containing monomer include hydrocarbon-based olefins such as ethylene, propylene, and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), Ethyl Vinyl Ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organosilicon compounds having reactive α, β -unsaturated groups such as Vinyltrimethoxysilane (VSi), vinyltriethoxysilane, and vinyltris (methoxyethoxy) silane; acrylic esters such as methyl acrylate and ethyl acrylate; methacrylates such as methyl methacrylate and ethyl methacrylate; vinyl esters such as vinyl acetate, vinyl benzoate, and "VeoVA" (trade name, vinyl ester manufactured by shell company); and so on. Among these, alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organosilicon compounds having a reactive α, β -unsaturated group are preferable.

Among these, the fluorine-containing resin particles are preferably particles having a high fluorination rate, more preferably particles of Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and the like, and particularly preferably particles of PTFE, FEP, PFA.

In the fluorine-containing resin particles, each 10⁶The number of carboxyl groups in the number of carbon atoms is preferably 0 to 30, more preferably 0 to 20.

Here, the carboxyl group of the fluorine-containing resin particle is, for example, a carboxyl group derived from a terminal carboxylic acid contained in the fluorine-containing resin particle.

Examples of the method for reducing the amount of carboxyl groups in the fluorine-containing resin particles include: 1) a method of not irradiating with radiation during the production of the particles, a method of 2) irradiating with radiation under a condition where oxygen is absent or under a condition where the oxygen concentration is reduced, or the like.

The amount of carboxyl groups in the fluorine-containing resin particles is measured as described in Japanese patent application laid-open No. 4-20507 or the like.

The fluororesin pellets were preformed by a press machine to prepare a film having a thickness of about 0.1 mm. The produced film was subjected to infrared absorption spectrometry. The fluorine-containing resin particles having carboxylic acid terminals completely fluorinated, which were prepared by contacting fluorine gas with the fluorine-containing resin particles, were also subjected to infrared absorption spectrometry, and the number of terminal carboxyl groups (per 10) was determined from the difference spectrum of the fluorine-containing resin particles and fluorine gas according to the following formula⁶Number of carbon atoms) ═ l × K/t

l: absorbance of the solution

K: correction factor

t: thickness of film (mm)

The absorption wavenumber of carboxyl is 3560cm^-1The correction coefficient is 440.

Examples of the fluorine-containing resin particles include particles obtained by irradiation with radiation (also referred to as "radiation-irradiation type fluorine-containing resin particles" in the present specification), particles obtained by polymerization (also referred to as "polymerization type fluorine-containing resin particles" in the present specification), and the like.

The radiation-irradiated fluororesin pellets (fluororesin pellets obtained by irradiation with radiation) are fluororesin pellets obtained by polymerizing radiation and granulating the fluororesin pellets at the same time, or fluororesin pellets obtained by reducing the amount of the fluororesin pellets after polymerization by decomposition by irradiation with radiation and micronizing the fluororesin pellets.

The radiation irradiation type fluorine-containing resin particles also contain a large amount of carboxyl groups because they generate a large amount of carboxylic acids by irradiation with radiation in the air.

On the other hand, the polymerizable fluororesin particles (fluororesin particles obtained by polymerization) mean fluororesin particles which are pelletized while being polymerized by suspension polymerization, emulsion polymerization, or the like and which have not been irradiated with radiation.

The fluorine-containing resin particles may be polymerized fluorine-containing resin particles. As described above, the polymerizable fluororesin particles are fluororesin particles that are polymerized and granulated by a suspension polymerization method, an emulsion polymerization method, or the like, and are not irradiated with radiation.

The production of the fluorine-containing resin particles by the suspension polymerization method is, for example, the following method: the monomer for forming the fluorine-containing resin is suspended in a dispersion medium together with additives such as a polymerization initiator and a catalyst, and the polymer is pelletized while polymerizing the monomer.

The production of the fluorine-containing resin particles by the emulsion polymerization method is, for example, the following method: the monomer for forming the fluorine-containing resin is emulsified in a dispersion medium together with additives such as a polymerization initiator and a catalyst by a surfactant (i.e., an emulsifier), and the polymer is pelletized while polymerizing the monomer.

In particular, the fluorine-containing resin particles may be particles obtained without being irradiated with radiation in the production step.

The fluororesin pellets may be radiation-irradiated fluororesin pellets obtained by irradiating the fluororesin pellets with radiation under conditions where oxygen is not present or where the oxygen concentration is decreased.

The average particle diameter of the fluorine-containing resin particles is not particularly limited, but is preferably 0.2 μm to 4.5 μm, more preferably 0.2 μm to 4 μm.

The average particle diameter of the fluorine-containing resin particles is a value measured by the following method.

The maximum diameter of the fluororesin particles (secondary particles obtained by aggregating the primary particles) is measured by observation with an SEM (scanning electron microscope) at a magnification of 5000 or more, for example, and the average value obtained by measuring 50 particles is taken as the average particle diameter of the fluororesin particles. Note that JSM-6700F manufactured by japan electronics was used as the SEM, and a secondary electron image with an acceleration voltage of 5kV was observed.

From the viewpoint of dispersion stability, the specific surface area (BET specific surface area) of the fluorine-containing resin particles is preferably 5m²15m above g²A ratio of 7m or less, more preferably²13m above g²The ratio of the carbon atoms to the carbon atoms is less than g.

The specific surface area was measured by a nitrogen substitution method using a BET specific surface area measuring instrument (manufactured by Shimadzu corporation: Flowseap II 2300).

From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles is preferably 0.2g/ml to 0.5g/ml, more preferably 0.3g/ml to 0.45 g/ml.

The apparent density is a value measured according to JIS K6891 (1995).

The melting temperature of the fluorine-containing resin particles is preferably 300 ℃ to 340 ℃ and more preferably 325 ℃ to 335 ℃.

The melting temperature is a melting point measured according to JIS K6891 (1995).

In the case where the charge transport layer is the outermost surface layer, the area occupied by the fluorine-containing resin particles measured on the surface thereof is preferably 0.33% to 1.1%, more preferably 0.36% to 0.95%, and still more preferably 0.38% to 0.90%, from the viewpoint of suppressing the generation of streak-like image defects and residual potential caused by friction between the photoreceptor and a contact member thereof due to vibration.

The area occupied by the fluorine-containing resin particles measured on the surface of the charge transport layer is set to be within the above range, and a large number of fluorine-containing resin particles having a high negative polarity are present on the surface of the charge transport layer. Thus, even when the photoreceptor and a member in contact with the photoreceptor rub against each other due to vibration during conveyance, positive charge due to the rubbing can be more easily eliminated, and frictional charging of the site where the photoreceptor is rubbed against the positive electrode can be further suppressed. Therefore, even if the photoreceptor is charged during image formation, the surface potential of the photoreceptor is less likely to be uneven in a stripe shape, and generation of stripe-shaped image defects and residual potential due to rubbing of the photoreceptor and a contact member thereof caused by vibration can be further suppressed.

A method for measuring the occupied area of the fluorine-containing resin particles will be described. The surface of the charge transport layer was observed with a Scanning Electron Microscope (SEM) over a range of 120. mu. m.times.90 μm, and the total area of the fluororesin particles exposed on the surface of the charge transport layer was calculated and divided by the observed area value (i.e., 120. mu. m.times.90 μm), thereby calculating the area occupied by the fluororesin particles.

The content of the fluorine-containing resin particles is preferably 1 mass% to 20 mass%, more preferably 5 mass% to 15 mass%, and still more preferably 7 mass% to 10 mass% with respect to the charge transport layer.

Concentration of fluorine atom-

In the photoreceptor of the present embodiment, when the charge transport layer is the outermost surface layer, the fluorine atom concentration measured on the surface thereof is 1.5 times or more and 5.0 times or less the fluorine atom concentration measured at a depth of 1 μm from the surface of the charge transport layer.

By setting the fluorine atom concentration of the charge transport layer to the above-described configuration, a large number of fluorine-containing resin particles are contained on the surface of the charge transport layer, and the generation of a streak-like image defect and a residual potential caused by rubbing of the photoreceptor and a contact member thereof due to vibration can be suppressed.

The fluorine atom concentration measured on the surface of the charge transport layer is preferably 2.0 times or more and 5.0 times or less, more preferably 2.5 times or more and 4.0 times or less, of the fluorine atom concentration measured at a depth of 1 μm from the surface of the charge transport layer, from the viewpoint of suppressing the generation of streak-like image defects and the residual potential caused by rubbing of the photoreceptor and the contact member thereof due to vibration.

The fluorine atom concentration was measured by X-ray Photoelectron Spectroscopy (XPS). First, the surface of the charge transport layer was analyzed by XPS method, and the concentration of fluorine atoms in all the elements was calculated. Next, sputtering was performed from the surface of the charge transport layer to a depth of 1 μm, so that a portion of the charge transport layer having a depth of 1 μm from the surface was exposed, and the surface was analyzed by XPS method, thereby calculating the concentration of fluorine atoms in all the elements.

The measurement conditions of XPS were set to 40kV in tube voltage and 90mA in tube current.

Additives, formation method and film thickness

Other known additives may be included in the charge transport layer.

As the additive, for example, a dispersant is preferable.

The dispersant is preferably a dispersant containing a fluorine element, and specifically, a fluorine-containing graft polymer can be mentioned.

Examples of the fluorine-containing graft polymer include a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluoroalkyl group (hereinafter, also referred to as "fluoroalkyl group-containing polymer").

Specific examples of the fluorine-containing graft polymer include homopolymers of (meth) acrylates having a fluoroalkyl group, random or block copolymers of (meth) acrylates having a fluoroalkyl group and monomers having no fluorine atom, and the like. The term (meth) acrylate refers to both acrylate and methacrylate.

Examples of the (meth) acrylate having a fluoroalkyl group include 2,2, 2-trifluoroethyl (meth) acrylate and 2,2,3,3, 3-pentafluoropropyl (meth) acrylate.

Examples of the monomer having no fluorine atom include (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-ester (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and mixtures thereof, Methoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, hydroxyethyl o-phenylphenol (meth) acrylate, o-phenylphenol glycidyl ether (meth) acrylate.

Further, as the fluorine-containing graft polymer, specifically, there can be mentioned a block or branched polymer disclosed in the specification of U.S. Pat. No. 5637142 and Japanese patent No. 4251662. Further, specific examples of the fluorine-containing graft polymer include a fluorine-based surfactant.

The content of the fluorine-containing graft polymer is preferably 1.0 mass% or more and 15.0 mass% or less, more preferably 2.0 mass% or more and 10.0 mass% or less, and further preferably 3.0 mass% or more and 8.0 mass% or less with respect to the content of the fluorine-containing resin particles.

In the case where the charge transport layer is the outermost surface layer, it is preferable that the fluorine-containing graft polymer is a kind and a content as described above, since a large amount of fluorine-containing resin particles are easily contained on the surface of the charge transport layer, and the fluorine atom concentration of the charge transport layer is easily constituted as described above.

The formation of the charge transport layer is not particularly limited, and a known formation method can be used, and for example, the formation can be performed as follows: a charge transport layer is formed by forming a coating film of a charge transport layer forming coating liquid in which the above components are added to a solvent, drying the coating film, and heating the coating film as necessary.

Examples of the solvent used for preparing the coating liquid for forming a charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and vinyl chloride; and common organic solvents such as cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents may be used alone or in combination of 2 or more.

Examples of the coating method for coating the charge transport layer forming coating liquid on the charge generating layer include common methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The film thickness of the charge transport layer is set, for example, in the range of preferably 5 μm to 50 μm, more preferably 10 μm to 30 μm.

(surface protective layer)

The surface protective layer is provided on the photosensitive layer as needed. The surface protective layer is provided, for example, for the purpose of preventing chemical changes of the photosensitive layer at the time of charging or further improving the mechanical strength of the photosensitive layer.

Therefore, a layer composed of a cured film (crosslinked film) may be applied as the surface protective layer. Examples of the layer include the layers shown in 1) or 2) below.

1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule (i.e., a layer containing a polymer or a crosslinked body of the reactive group-containing charge transport material)

2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge-transporting skeleton but having a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked body of the reactive group-containing non-charge transport material)

Examples of the reactive group-containing charge transport material include a chain-locking polymerizable group, an epoxy group, -OH, -OR [ wherein R represents an alkyl group]、-NH₂、-SH、-COOH、-SiR^Q1 _3-Qn(OR^Q2)_Qn[ wherein R^Q1Represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R^Q2Represents a hydrogen atom, an alkyl group or a trialkylsilyl group. Qn represents an integer of 1 to 3]And the like known reactive groups.

The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specifically, the resin composition may contain at least one member selected from the group consisting of a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof, because of its excellent reactivity.

The charge-transporting skeleton of the reactive group-containing charge-transporting material is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include the following structures: the skeleton of the structure is derived from a nitrogen-containing hole-transporting compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and is conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferable.

The reactive group-containing charge transport material, the non-reactive charge transport material, and the reactive group-containing non-charge transport material each having a reactive group and a charge transport skeleton may be selected from known materials.

Other known additives may be included in the surface protective layer.

The formation of the surface protection layer is not particularly limited, and a known formation method can be used, and for example, the formation can be performed as follows: a coating film of a coating liquid for forming a surface protective layer, which is obtained by adding the above components to a solvent, is formed, and the coating film is dried and, if necessary, subjected to curing treatment such as heating, thereby forming a surface protective layer.

Examples of the solvent used for preparing the coating liquid for forming the surface protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butyl alcohol. These solvents may be used alone or in combination of 2 or more.

The coating liquid for forming the surface protective layer may be a solvent-free coating liquid.

Examples of the method for applying the coating liquid for forming a surface protective layer to the photosensitive layer (for example, charge transport layer) include common methods such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, and a curtain coating method.

The film thickness of the surface protective layer is set in a range of preferably 1 μm to 20 μm, and more preferably 2 μm to 10 μm, for example. When the surface protective layer is the outermost surface layer, the surface protective layer contains fluorine-containing resin particles. The fluororesin particles contained in the surface protective layer are the same as those described above, and therefore, detailed description of the fluororesin particles is omitted.

(Single layer type photosensitive layer)

The single-layer type photosensitive layer (charge generating/charge transporting layer) is, for example, a layer containing a charge generating material and a charge transporting material, and if necessary, a binder resin and other known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. In the case where the monolayer type photosensitive layer is the outermost surface layer, the monolayer type photosensitive layer contains fluorine-containing resin particles.

In the monolayer type photosensitive layer, the content of the charge generating material may be 0.1 mass% or more and 10 mass% or less, preferably 0.8 mass% or more and 5 mass% or less, based on the total solid content. In the monolayer type photosensitive layer, the content of the charge transport material may be5 mass% or more and 50 mass% or less with respect to the total solid content.

The method of forming the single-layer photosensitive layer is the same as the method of forming the charge generating layer and the charge transporting layer.

The thickness of the monolayer photosensitive layer may be, for example, 5 μm to 50 μm, and preferably 10 μm to 40 μm.

< image Forming apparatus (and Process Cartridge) >

The image forming apparatus of the present embodiment includes: an electrophotographic photoreceptor; a charging mechanism for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and a transfer mechanism that transfers the toner image to a surface of the recording medium. The photoreceptor of the present embodiment is applied as an electrophotographic photoreceptor.

The following known image forming apparatuses can be applied to the image forming apparatus of the present embodiment: a device including a fixing mechanism for fixing the toner image transferred to the surface of the recording medium; a direct transfer type device for directly transferring the toner image formed on the surface of the electrophotographic photoreceptor to a recording medium; an intermediate transfer type device for primarily transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of an intermediate transfer member and secondarily transferring the toner image transferred to the surface of the intermediate transfer member to the surface of a recording medium; a device including a cleaning mechanism for cleaning the surface of the electrophotographic photoconductor before charging after the toner image is transferred; a device including a charge removing mechanism for irradiating a charge removing light to the surface of the electrophotographic photoreceptor after the toner image is transferred and before charging to remove the charge; a device provided with an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and lowering the relative temperature; and so on.

In the case of an intermediate transfer system apparatus, the transfer mechanism is configured, for example, as follows: the image forming apparatus includes an intermediate transfer body having a surface onto which a toner image is transferred, a primary transfer mechanism for primary-transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the intermediate transfer body, and a secondary transfer mechanism for secondary-transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type (development type using a liquid developer) image forming apparatus.

In the image forming apparatus of the present embodiment, for example, a portion including the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge provided with the photoreceptor of the present embodiment is suitably used. The process cartridge may include, in addition to the electrophotographic photoreceptor, at least one member selected from the group consisting of a charging mechanism, an electrostatic latent image forming mechanism, a developing mechanism, and a transfer mechanism.

An example of the image forming apparatus according to the present embodiment is described below, but the present invention is not limited to this. The main portions shown in the drawings will be described, and the other portions will not be described.

Fig. 2 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

As shown in fig. 2, the image forming apparatus 100 of the present embodiment includes: a process cartridge 300 provided with an electrophotographic photoreceptor 7; an exposure device 9 (an example of an electrostatic latent image forming mechanism); a transfer device 40 (primary transfer device); and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photoreceptor 7 can be exposed through the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 with the intermediate transfer body 50 interposed therebetween, and the intermediate transfer body 50 is disposed so that a part thereof comes into contact with the electrophotographic photoreceptor 7. Although not shown, there is also a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and a secondary transfer device (not shown) correspond to an example of a transfer mechanism.

The process cartridge 300 in fig. 2 integrally supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging mechanism), a developing device 11 (an example of a developing mechanism), and a cleaning device 13 (an example of a cleaning mechanism) in a casing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed so as to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

Fig. 2 shows an example in which the image forming apparatus includes a fibrous member 132 (roll-like) for supplying the lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a cleaning-assisting fibrous member 133 (flat brush-like), but these members are arranged as necessary.

The following describes each configuration of the image forming apparatus according to the present embodiment.

Charging device

As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, or the like is used. Further, a non-contact type roller charger, a scorotron charger using corona discharge, a corona charger, and other chargers known per se may be used.

-exposure device

Examples of the exposure device 9 include an optical system device that exposes the surface of the electrophotographic photoreceptor 7 to a predetermined image by using light such as a semiconductor laser, LED light, or liquid crystal light valve light. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near infrared having an oscillation wavelength in the vicinity of 780nm is the mainstream. However, the wavelength is not limited to this, and a laser beam having an oscillation wavelength of approximately 600nm or a laser beam having an oscillation wavelength of 400nm to 450nm as a blue laser beam may be used. In addition, in order to form a color image, a surface-emission type laser light source of a type that can output multiple beams is also effective.

Developing device

The developing device 11 is, for example, a general developing device that performs development with or without contact with a developer. The developing device 11 is not particularly limited as long as it has the above-described functions, and may be selected according to the purpose. Examples of the known developing device include a known developing device having a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, or the like. Among them, a developing roller having a developer retained on the surface is preferably used.

The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. The developer can be any known developer.

Cleaning device

The cleaning device 13 is a cleaning blade type device provided with a cleaning blade 131.

The cleaning blade 131 preferably contacts the electrophotographic photoreceptor 7 so that the contact pressure with the electrophotographic photoreceptor 7 is 1.0g/mm to 4.0 g/mm.

Here, the contact pressure with respect to the electrophotographic photoreceptor 7 means a load per unit length of the contact portion of the electrophotographic photoreceptor 7 applied by the cleaning blade 131, that is, a linear pressure.

When the contact pressure of the cleaning blade 131 with respect to the electrophotographic photoreceptor 7 is in the above range, the friction generated by the friction between the electrophotographic photoreceptor 7 and the cleaning blade 131 due to vibration is reduced, the surface of the electrophotographic photoreceptor 7 is less likely to be triboelectrically charged, and the generation of streaky image defects and residual potential are suppressed, which is preferable.

The contact pressure of the cleaning blade 131 against the electrophotographic photoreceptor 7 is more preferably 1.5g/mm or more and 3.5g/mm or less, and still more preferably 2.0g/mm or more and 3.0g/mm or less, from the viewpoint of suppressing the generation of streak-like image defects and residual potential caused by rubbing of the photoreceptor and the contact member thereof due to vibration.

In addition to the cleaning blade system, a brush cleaning system or a simultaneous development cleaning system may be used.

-transfer means

Examples of the transfer device 40 include a contact type transfer charger using a belt, a roller, a film, a rubber blade, or the like, a scorotron type transfer charger using corona discharge, a corona transfer charger, and other transfer chargers known per se.

An intermediate transfer body

As the intermediate transfer member 50, a belt-shaped transfer member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, or the like, which is provided with semiconductivity, is used. In addition, as the form of the intermediate transfer member, a drum-shaped transfer member other than a belt-shaped transfer member may be used.

Fig. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

The image forming apparatus 120 shown in fig. 3 is a tandem multicolor image forming apparatus having 4 process cartridges 300 mounted thereon. In the

image forming apparatus

120, 4 process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and 1 electrophotographic photoreceptor is used for each 1 color. Image forming apparatus 120 has the same configuration as image forming apparatus 100, except that it is a tandem system.

EXAMPLE 2 EXAMPLE

Electrophotographic photoreceptor

The electrophotographic photoreceptor of the present embodiment has a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer contains fluorine-containing resin particles.

In the electrophotographic photoreceptor of the present embodiment, the ratio (N2/N1) of the number density (N1) of the aggregates of the fluororesin particles in a first region from the surface to 1/2 where the layer thickness is equal to or greater than 0.95 to the number density (N2) of the aggregates of the fluororesin particles in a second region from 1/2 where the film thickness is equal to or greater than the bottom surface of the outermost surface layer.

In the electrophotographic photoreceptor of the present embodiment, the ratio (S2/S1) between the area ratio (S1) of the fluorine-containing resin particles in the first region from the surface to 1/2 where the layer thickness is equal to and the area ratio (S2) of the fluorine-containing resin particles in the second region from 1/2 where the film thickness is equal to and equal to the bottom surface of the outermost surface layer is within the range of 1 ± 0.1.

In an electrophotographic photoreceptor having an outermost surface layer containing fluorine-containing resin particles, the fluorine-containing resin particles have an effect of improving the wear resistance when a cleaning blade is brought into contact with the outermost surface layer. However, the fluororesin particles tend to have high flocculation property, and therefore, a technique of dispersing the fluororesin particles in a nearly uniform state throughout the entire layer while suppressing the flocculation of the particles is adopted for the outermost surface layer including the particles. However, when the fluorine-containing resin particles are dispersed in a nearly uniform state, the fluorine-containing resin particles tend to physically inhibit the charge transport property of the outermost surface layer. As a result, charge transport properties in the outermost surface layer, that is, sensitivity, tend to decrease when the electrophotographic photoreceptor is exposed to light.

On the other hand, the electrophotographic photoreceptor of the present embodiment has both excellent sensitivity and excellent wear resistance by having the above-described configuration. The reason is not necessarily clear, but is presumed as follows.

In the electrophotographic photoreceptor of the present embodiment, the ratio (N2/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in a first region from the surface to 1/2 where the layer thickness is greater than the number density (N2) of the aggregates of the fluorine-containing resin particles in a second region from 1/2 where the film thickness is greater than the bottom surface of the outermost surface layer is less than 0.95. That is, in the first region (the surface side in contact with the cleaning blade) and the second region (the conductive substrate side), the number of aggregates of the fluorine-containing resin particles in the first region is small, and the fluorine-containing resin particles are dispersed in a nearly uniform state. Therefore, it is considered that the wear resistance is exerted on the surface side in contact with the cleaning blade. Further, the increase in the number of aggregates in the second region increases the region where the fluorine-containing resin particles are not present, and physical inhibition of the charge transport property of the outermost surface layer by the fluorine-containing resin particles is suppressed. As a result, it is considered that the decrease in sensitivity can be suppressed.

In the electrophotographic photoreceptor of the present embodiment, the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in the first region to the area ratio (S2) of the fluorine-containing resin particles in the second region is 1 ± 0.1 or less. That is, the amount of the fluorine-containing resin particles present in the first region (the surface side in contact with the cleaning blade) and the second region (the conductive substrate side) is the same regardless of the degree of aggregation. Therefore, for example, even when the electrophotographic photoreceptor of the present embodiment is driven for a long period of time, it is considered that the abrasion resistance is excellent.

Layer constitution of electrophotographic photoreceptor

The layer structure of the electrophotographic photoreceptor is described below with reference to the drawings.

Fig. 4 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor of the present embodiment. The electrophotographic photoreceptor 107A has the following structure: an undercoat layer 101 is provided on a conductive substrate 104, and a charge generation layer 102, a charge transport layer 103, and a surface protection layer 106 are formed thereon in this order. The electrophotographic photoreceptor 107A has a photosensitive layer 105 functionally separated into a charge generation layer 102 and a charge transport layer 103. Hereinafter, the electrophotographic photoreceptor 107A having the laminated photosensitive layer 105 shown in fig. 4 is also referred to as a "laminated photoreceptor".

Fig. 5 is a schematic cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor of the present embodiment. The electrophotographic photoreceptor 107B has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a photosensitive layer 105 and a surface protective layer 106 are formed thereon in this order. The electrophotographic photoreceptor 107B has a single-layer type photosensitive layer in which functions are integrated by containing a charge generating material and a charge transporting material in the same photosensitive layer 105. Hereinafter, the electrophotographic photoreceptor 107B having the single-layer photosensitive layer 105 shown in fig. 5 is also referred to as a "single-layer photoreceptor".

The electrophotographic photoreceptor in the present embodiment may be provided with the undercoat layer 101 and the surface protective layer 106, or may not be provided.

The respective layers of the electrophotographic photoreceptor of the present embodiment will be described in detail below. The conductive substrate 104, the undercoat layer 101, the intermediate layer, the charge generation layer 102, and the monolayer photosensitive layer according to embodiment 2 are the same as those according to embodiment 1, and therefore, the description thereof will be omitted. Note that the reference numerals are omitted for description.

Outermost surface layer

The electrophotographic photoreceptor of the present embodiment contains fluorine-containing resin particles in the outermost surface layer.

In the electrophotographic photoreceptor of the present embodiment, the ratio (N2/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in a first region from the surface to 1/2 where the layer thickness is greater than the number density (N2) of the aggregates of the fluorine-containing resin particles in a second region from 1/2 where the film thickness is greater than the bottom surface of the outermost surface layer is less than 0.95.

In the electrophotographic photoreceptor of the present embodiment, the ratio (S2/S1) of the area ratio (S1) of the fluorine-containing resin particles in the first region from the surface to 1/2 where the layer thickness is equal to the area ratio (S2) of the fluorine-containing resin particles in the second region from 1/2 where the film thickness is equal to the bottom surface of the outermost surface layer is within the range of 1 ± 0.1.

In the case where the electrophotographic photoreceptor has a surface protective layer, the outermost surface layer refers to the surface protective layer.

In the case of a laminate type photoreceptor having no surface protective layer for an electrophotographic photoreceptor, the outermost surface layer refers to a charge transport layer.

In the case of a single layer type photoreceptor having no surface protective layer of the electrophotographic photoreceptor, the outermost surface layer means a photosensitive layer.

[ State of outermost surface layer ]

The term "aggregate of fluororesin particles" means a group of primary particles of fluororesin particles present at an interparticle distance of not more than 1 μm. When no particle is present within 1 μm around the primary particle, 1 primary particle is counted as 1 aggregate.

The primary particles constituting the aggregate may be present in a region within 1 μm of each other, and may be in any state of a state in which the particles are in contact with each other, a state in which the particles are not in contact with each other but are adjacent to each other, and a state including both of them.

The inter-particle distance is the shortest straight-line distance when connecting arbitrary 2 points of the outer edges (surfaces) of adjacent primary particles.

For example, when an aggregate is present on a boundary line between the first region and the second region or a boundary line between the second region and the third region, the aggregate is calculated as a region in which the area of the aggregate is larger.

(ratio of number density of aggregates of fluorine-containing resin particles in each region) · ratio (N2/N1)

In the electrophotographic photoreceptor of the present embodiment, the ratio (N2/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1/2 where the layer thickness is equal to or greater than the layer thickness to the number density (N2) of the aggregates of the fluorine-containing resin particles in the second region from 1/2 where the film thickness is equal to or greater than the bottom surface of the outermost surface layer is less than 0.95, and is preferably 0.1 to 0.8, more preferably 0.2 to 0.7, from the viewpoint of producing an electrophotographic photoreceptor excellent in both sensitivity and wear resistance.

Ratio (N3/N1)

In the electrophotographic photoreceptor of the present embodiment, from the viewpoint of producing an electrophotographic photoreceptor excellent in both sensitivity and abrasion resistance and the viewpoint of suppressing the occurrence of color dots due to the incorporation of needle-like foreign matter, the ratio (N3/N1) of the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1/2 where the layer thickness is from the surface of the outermost surface layer to the number density (N3) of the aggregates of the fluorine-containing resin particles in the third region from 9/10 where the layer thickness is from the surface of the outermost surface layer to the bottom surface of the outermost surface layer is preferably 0.9 or less, more preferably 0.7 or less. The ratio (N3/N1) is also preferably 0.2 to 0.8, more preferably 0.3 to 0.7.

Conventionally, when needle-like conductive foreign matter such as carbon fibers is mixed in an electrophotographic photoreceptor, the foreign matter penetrates into the outermost surface layer, and insulation breakdown occurs in the penetrated region due to voltage from a charging member, and leakage current is likely to occur. In the region where the leakage current occurs, charging becomes poor, and color dots may occur when an image is formed. This phenomenon is particularly remarkable in an electrophotographic photoreceptor having an outermost surface layer (particularly, a charge transport layer) containing fluorine-containing resin particles, and the interface between the fluorine-containing resin particles and the resin is weak, easily causing insulation breakdown.

On the other hand, in the electrophotographic photoreceptor of the present embodiment, the number density of the aggregates of the fluororesin particles in the second region becomes lower by setting the ratio (N3/N1) to be in the above range in particular. Therefore, even when the conductive foreign matter penetrates, insulation breakdown is less likely to occur. As a result, it is considered that generation of color dots due to leakage current can be suppressed.

Respective number Density (N1, N2 and N3)

From the viewpoint of obtaining an electrophotographic photoreceptor having more excellent sensitivity and abrasion resistance, the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1/2, the layer thickness of which is the layer thickness of the outermost surface layer, is preferably 5 particles/100 μm ²50 pieces/100 mu m²The number of them is preferably 6/100. mu.m²Above 30 pieces/100 mu m²The number of them is preferably 8/100. mu.m²Above 20 pieces/100 μm²The following.

The method of adjusting the ratio (N2/N1) and the ratio (N3/N1) of the number density of the aggregates of the fluorine-containing resin particles in each region is not particularly limited, and examples thereof include: in the formation of the outermost surface layer, (1) a method of adjusting the number of treatments by a homogenizer when preparing a coating liquid containing fluorine-containing resin particles; (2) a method of adjusting the amount or type of the fluorine-containing resin particles; (3) a method of stepwise forming a coating film having a concentration difference by using a plurality of coating liquids having different solid content concentrations of the fluororesin particles while adjusting the content of the fluororesin particles in the outermost surface layer; (4) a method of adjusting the drying temperature of the coating film in stages; (5) a method of increasing the relative speed of the material to be coated and the coating liquid at the time of coating; and the like.

The method for adjusting the number density (N1 to N3) of the aggregates of the fluorine-containing resin particles in each region is not particularly limited, and examples thereof include: in the formation of the outermost surface layer, (1) a method of adjusting the number of treatments by a homogenizer when preparing a coating liquid containing fluorine-containing resin particles; (2) a method of adjusting the amount or type of the fluorine-containing resin particles; (3) a method of stepwise forming a coating film having a concentration difference by using a plurality of coating liquids having different solid content concentrations of the fluororesin particles while adjusting the content of the fluororesin particles in the outermost surface layer; (4) a method of adjusting the drying temperature of the coating film in stages; (5) a method of increasing the relative speed of the material to be coated and the coating liquid at the time of coating; and the like.

The number density of the aggregates of the fluorine-containing resin particles (N1 to N3) and the above-mentioned ratio of the outermost surface layer (N2/N1, N3/N1) can be confirmed as follows. (1) The outermost surface layer of the electrophotographic photoreceptor was cut in the thickness direction to obtain a test piece having the cross section as an observation surface.

(2) The observation surface of the test piece was observed with a Scanning Electron Microscope (SEM) apparatus (JSM-6700F, manufactured by Nippon electronics Co., Ltd.), an image was taken, the number of aggregates of the fluorine-containing resin particles in the first region from the surface (i.e., the layer thickness of 0 μm) to 1/2, which is the layer thickness, of the outermost surface layer was calculated by image analysis and converted into the number per unit area, and this value was defined as the number density of the fluorine-containing resin particles (N1). Similarly, the number of aggregates of the fluororesin particles in each of the second region and the third region is calculated, and the number is calculated as the number per unit area.

(3) The sections of the outermost surface layer at arbitrary 3 places in the electrophotographic photoreceptor were subjected to the above (1) and (2), and the arithmetic average thereof was taken as the number density of the fluorine-containing resin particles in each region (N1, N2, and N3).

(4) The ratios (N2/N1) and (N3/N1) were obtained.

(ratio of area ratios of fluorine-containing resin particles in respective regions) to (S2/S1)

In the electrophotographic photoreceptor of the present embodiment, the ratio (S2/S1) of the area ratio (S1) of the fluororesin particles in the first region from the surface to 1/2 of the layer thickness of the outermost surface layer to the area ratio (S2) of the fluororesin particles in the second region from 1/2 of the film thickness to the bottom surface of the outermost surface layer is in the range of 1 ± 0.1, and is preferably 0.97 to 1.07, and more preferably 0.95 to 1.05, from the viewpoint of producing an electrophotographic photoreceptor having more excellent abrasion resistance.

The method of adjusting the area ratio of the fluorine-containing resin particles in each region (S2/S1) is not particularly limited, and examples thereof include: in the formation of the outermost surface layer, (1) a method of adjusting the number of treatments by a homogenizer when preparing a coating liquid containing fluorine-containing resin particles; (2) a method of adjusting the amount or type of the fluorine-containing resin particles; (3) a method of stepwise forming a coating film having a concentration difference by using a plurality of coating liquids having different solid content concentrations of the fluororesin particles while adjusting the content of the fluororesin particles in the outermost surface layer; (4) a method of adjusting the drying temperature of the coating film in stages; (5) a method of increasing the relative speed of the material to be coated and the coating liquid at the time of coating; and the like.

The ratio of the area ratios of the aggregates of the fluorine-containing resin particles (S2/S1) was confirmed as follows. (1) The outermost surface layer of the electrophotographic photoreceptor was cut in the thickness direction to obtain a test piece having the cross section as an observation surface.

(2) The observation surface of the test piece was observed with a Scanning Electron Microscope (SEM) (scanning Electron microscope) apparatus (S-4100, manufactured by Hitachi, Ltd.), an image was taken, and the image was introduced into an image analyzer (LUZEXIII, manufactured by NIRECO, Ltd.). Then, the total area of all the aggregates of the fluorine-containing resin particles in the first region from the surface (i.e., the layer thickness of 0 μm) to 1/2, which is the layer thickness, of the outermost surface layer was determined by image analysis. Then, the area ratio of the aggregate of the fluorine-containing resin particles to the area of the first region was determined. Similarly, the area ratio of the aggregates of the fluorine-containing resin particles in the second region is determined.

(3) The sections of the outermost surface layer at arbitrary 3 places in the electrophotographic photoreceptor were subjected to the above (1) and (2), and the arithmetic average thereof was taken as the area ratio of the fluorine-containing resin particles in each of the first region and the second region (S1 and S2).

(4) The ratio is obtained (S2/S1).

(ratio of average diameter of aggregates of fluorine-containing resin particles in each region) · ratio (D2/D1)

In the electrophotographic photoreceptor of the present embodiment, from the viewpoint of producing an electrophotographic photoreceptor having more excellent sensitivity and abrasion resistance and from the viewpoint of suppressing the occurrence of color dots due to the incorporation of needle-like foreign matter, the ratio (D2/D1) of the average diameter (D1) of the aggregate of the fluorine-containing resin particles in a first region from the surface to 1/2 in the layer thickness of the outermost surface layer to the average diameter (D2) of the aggregate of the fluorine-containing resin particles in a second region from 1/2 in the film thickness to the bottom surface of the outermost surface layer is preferably 2 or more, more preferably 3 or more and 30 or less, and still more preferably 5 or more and 30 or less.

The method for adjusting the ratio of the average diameters of the aggregates of the fluorine-containing resin particles in each region (D2/D1) is not particularly limited, and examples thereof include: in the formation of the outermost surface layer, (1) a method of adjusting the number of treatments by a homogenizer when preparing a coating liquid containing fluorine-containing resin particles; (2) a method of adjusting the amount or type of the fluorine-containing resin particles; (3) a method of stepwise forming a coating film having a concentration difference by using a plurality of coating liquids having different solid content concentrations of the fluororesin particles while adjusting the content of the fluororesin particles in the outermost surface layer; (4) a method of adjusting the drying temperature of the coating film in stages; (5) a method of increasing the relative speed of the material to be coated and the coating liquid at the time of coating; and the like.

The ratio of the average diameters of the aggregates of the fluorine-containing resin particles (D2/D1) was confirmed as follows.

(1) The outermost surface layer of the electrophotographic photoreceptor was cut in the thickness direction to obtain a test piece having the cross section as an observation surface.

(2) The observation surface of the test piece was observed with a Scanning Electron Microscope (SEM) (scanning Electron microscope) apparatus (S-4100, manufactured by Hitachi, Ltd.), an image was taken, and the image was introduced into an image analyzer (LUZEXIII, manufactured by NIRECO, Ltd.). Then, the respective areas of all the aggregates of the fluororesin particles in the first region from the surface (i.e., the layer thickness of 0 μm) to 1/2 were determined by image analysis. Then, the equivalent circle diameter of each aggregate was calculated from the area value, and the 50% diameter (D50) at the cumulative frequency based on the number of the obtained equivalent circle diameters was defined as the average diameter (D1) of the aggregates of the fluorine-containing resin particles in the first region. Similarly, the average diameter of the aggregate of the fluorine-containing resin particles in the second region is determined (D2).

(3) The ratio (D2/D1) was obtained.

(Primary particle diameter of fluorine-containing resin particle in each region)

In the electrophotographic photoreceptor of the present embodiment, from the viewpoint of producing an electrophotographic photoreceptor more excellent in both sensitivity and abrasion resistance and from the viewpoint of suppressing the occurrence of color dots due to the incorporation of needle-like foreign substances, the primary particle diameter (D11) of the fluorine-containing resin particles in the first region from the surface to 1/2, which is the layer thickness, of the outermost surface layer and the primary particle diameter (D12) of the fluorine-containing resin particles in the second region from 1/2, which is the film thickness, to the bottom surface of the outermost surface layer are each preferably 20nm to 800nm, more preferably 50nm to 600nm, and still more preferably 100nm to 500 nm.

The primary particle diameter (D11 or D12) of the fluorine-containing resin particles in each region can be confirmed as follows. (1) The outermost surface layer of the electrophotographic photoreceptor was cut in the thickness direction to obtain a test piece having the cross section as an observation surface.

(2) The observation surface of the test piece was observed with a Scanning Electron Microscope (SEM) (scanning Electron microscope) apparatus (S-4100, manufactured by Hitachi, Ltd.), an image was taken, and the image was introduced into an image analyzer (LUZEXIII, manufactured by NIRECO, Ltd.). Then, the areas of all the fluorine-containing resin particles (primary particles) in the first region from the surface (i.e., the layer thickness of 0 μm) to 1/2 were determined by image analysis. Then, the equivalent circle diameter of each primary particle was calculated from the area value, and the 50% diameter (D50) at the cumulative frequency based on the number of the obtained equivalent circle diameters was defined as the primary particle diameter (D11) of the fluorine-containing resin particle in the first region. Similarly, the primary particle diameter of the fluorine-containing resin particles in the second region was determined (D12).

[ fluorine-containing resin particles ]

The outermost surface layer contains fluorine-containing resin particles. The fluorine-containing resin particles may be 1 type alone or 2 or more types in combination.

A carboxyl group

The fluorine-containing resin particles preferably contain no carboxyl group or a trace amount of the fluorine-containing resin particles. Specifically, the fluorine-containing resin particles are used for producing an electrophotographic photoreceptor having excellent chargeabilityThe number of carboxyl groups is 10 per unit⁶The number of carbon atoms is preferably 0 to 30, more preferably 0 to 20.

The carboxyl group of the fluorine-containing resin particle is a carboxyl group derived from a terminal carboxylic acid contained in the fluorine-containing resin particle.

The method for reducing the amount of carboxyl groups in the fluorine-containing resin particles is not particularly limited, and examples thereof include: a method in which the fluororesin is pelletized without being irradiated with radiation (1); (2) a method in which the irradiation is performed under a condition where oxygen is absent or under a condition where the oxygen concentration is reduced; and the like.

The amount of carboxyl groups in the fluorine-containing resin particles is measured as described in Japanese patent application laid-open No. 4-20507 or the like. The fluororesin pellets were preformed by a press machine to prepare a film having a thickness of about 0.1 mm. The produced film was subjected to infrared absorption spectrometry. The fluorine-containing resin particles having carboxylic acid terminals completely fluorinated, which were prepared by contacting fluorine gas with the fluorine-containing resin particles, were also subjected to infrared absorption spectrometry, and the number of terminal carboxyl groups (per 10) was determined from the difference spectrum of the fluorine-containing resin particles and fluorine gas according to the following formula⁶Number of carbon atoms).

The number of terminal carboxyl groups (per 10)⁶Number of carbon atoms) ═ l × K/t

l: absorbance of the solution

K: the correction coefficient,

t: thickness of film (mm)

Basic compound

The fluorine-containing resin particles preferably contain no basic compound or a trace amount of the basic compound. Specifically, the amount of the basic compound in the fluorine-containing resin particles is preferably 0ppm to 3ppm, more preferably 0ppm to 1.5ppm, and still more preferably 0ppm to 1.2ppm, from the viewpoint of producing an electrophotographic photoreceptor having excellent chargeability. Ppm is a mass basis.

Specific examples of the basic compound contained in the fluorine-containing resin particles include: 1) a basic compound derived from a polymerization initiator used when fluorine-containing resin particles are polymerized and simultaneously pelletized; 2) a basic compound used in a step of aggregating after polymerization; 3) an alkaline compound used as a dispersing aid for stabilizing the dispersion after polymerization; and so on.

Examples of the basic compound include: with an amine compound; hydroxides of alkali metals or alkaline earth metals; oxides of alkali metals or alkaline earth metals; acetates and the like (for example, amine compounds in particular); and the like.

The basic compound can be, for example, a basic compound having a boiling point (boiling point under normal pressure (1 atm)) of 40 ℃ to 130 ℃ (preferably 50 ℃ to 110 ℃, more preferably 60 ℃ to 90 ℃).

Examples of the amine compound include a primary amine compound, a secondary amine compound, and a tertiary amine compound.

Examples of the primary amine compound include methylamine, ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, hexylamine, 2-ethylhexylamine, sec-butylamine, allylamine, and methylhexylamine.

Examples of the secondary amine compound include dimethylamine, diethylamine, di-N-propylamine, diisopropylamine, di-N-butylamine, diisobutylamine, di-tert-butylamine, dihexylamine, bis (2-ethylhexyl) amine, N-isopropyl-N-isobutylamine, bis (2-ethylhexyl) amine, di-sec-butylamine, diallylamine, N-methylhexylamine, 3-methylpiperidine, 4-methylpiperidine, 2, 4-dimethylpiperidine, 2, 6-dimethylpiperidine, 3, 5-dimethylpiperidine, morpholine, and N-methylbenzylamine.

Examples of the tertiary amine compound include trimethylamine, triethylamine, tri-N-propylamine, triisopropylamine, tri-N-butylamine, triisobutylamine, tri-tert-butylamine, trihexylamine, tris (2-ethylhexyl) amine, N-methylmorpholine, N, N-dimethylallylamine, N-methyldiallylamine, triallylamine, N, N-dimethylallylamine, N, N, N ', N' -tetramethyl-1, 2-diaminoethane, N, N, N ', N' -tetramethyl-1, 3-diaminopropane, N, N, N ', N' -tetraallyl-1, 4-diaminobutane, N-methylpiperidine, pyridine, 4-ethylpyridine, N-propyldiallylamine, 3-dimethylaminopropanol, 2-ethylpyrazine, and the like, 2, 3-dimethylpyrazine, 2, 5-dimethylpyrazine, 2, 4-dimethylpyridine, 2, 5-dimethylpyridine, 3, 4-dimethylpyridine, 3, 5-dimethylpyridine, 2,4, 6-trimethylpyridine, 2-methyl-4-ethylpyridine, 2-methyl-5-ethylpyridine, N, N, N ', N' -tetramethyl-1, 6-hexanediamine, N-ethyl-3-hydroxypiperidine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methylpyridine, 4- (5-nonyl) pyridine, imidazole, N-methylpiperazine and the like.

As the hydroxide of an alkali metal or an alkaline earth metal, NaOH, KOH, Ca (OH) may be mentioned₂、Mg(OH)₂、Ba(OH)₂And the like.

Examples of the oxide of an alkali metal or an alkaline earth metal include CaO and MgO.

Examples of the acetate include zinc acetate and sodium acetate.

The method for reducing the amount of the basic compound contained in the fluorine-containing resin particles is not particularly limited, and examples thereof include: (1) a method of washing the granules with water, an organic solvent (alcohol such as methanol, ethanol, or isopropanol; tetrahydrofuran, or the like) or the like after the production of the granules; 2) a method in which the particles are heated (for example, to 200 ℃ to 250 ℃) after the production of the particles, and the basic compound is decomposed or gasified to be removed; and so on.

The amount of the basic compound contained in the fluorine-containing resin particles is measured as follows.

Pretreatment-

In the measurement of the outermost surface layer containing the fluorine-containing resin particles, a sample of the outermost surface layer is immersed in a solvent (for example, tetrahydrofuran), the fluorine-containing resin particles and substances other than the solvent-insoluble substances are dissolved in the solvent (for example, tetrahydrofuran), and then dropped into pure water, and the precipitate is filtered off. The PFOA-containing solution obtained at this time was collected. Further, the insoluble matter obtained by the filtration was dissolved in a solvent, and then, the solution was added dropwise to pure water, and the precipitate was filtered off. This operation was repeated 5 times in total. Then, 800mg of the fluorine-containing resin pellets were added to 1.5ml of chloroform, and the basic compound was eluted from the fluorine-containing resin pellets to obtain a measurement sample.

Determination of

On the other hand, using a basic compound solution (methanol solvent) of known concentration, a calibration curve (calibration curve of 0ppm to 100 ppm) was obtained from the values of the basic compound concentration and the peak area of the basic compound solution (methanol solvent) of known concentration by gas chromatography.

Then, the measurement sample was measured by gas chromatography, and the amount of the basic compound in the measurement sample was calculated from the obtained peak area and the calibration curve. The amount of the basic compound contained in the fluorine-containing resin particles is calculated by dividing the calculated amount of the basic compound in the measurement sample by the amount of the fluorine-containing resin particles used in the measurement sample. The measurement conditions were as follows.

Determination of conditions

Head space injector: (HP7694, manufactured by HP Co.)

The measuring machine: gas chromatography (HP6890 series, HP company manufacturing)

The detector: hydrogen Flame Ionization Detector (FID)

Column: (HP19091S-433, manufactured by HP Co.)

Sample heating time: for 10min

Split Ratio (Sprit Ratio): 300: 1

Flow rate: 1.0ml/min

Column temperature setting: 60 deg.C (3min), 60 deg.C/min, 200 deg.C (1min)

Fluorine-containing resin

Examples of the fluororesin constituting the fluororesin particles include: (1) particles of a homopolymer of a fluoroolefin, and (2) a copolymer of 1 or 2 or more species of fluoroolefin and a non-fluorinated monomer (i.e., a monomer having no fluorine atom) which is a copolymer of 2 or more species of fluoroolefin.

Examples of the fluoroolefin include a perhaloolefin such as Tetrafluoroethylene (TFE), perfluorovinyl ether, Hexafluoropropylene (HFP) or Chlorotrifluoroethylene (CTFE), a non-perfluoroolefin such as vinylidene fluoride (VdF), trifluoroethylene or vinyl fluoride. Among these, the fluoroolefin preferably contains 1 or more selected from the group consisting of VdF, TFE, CTFE, and HFP.

Examples of the non-fluorine-containing monomer include hydrocarbon-based olefins such as ethylene, propylene, and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), Ethyl Vinyl Ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organosilicon compounds having reactive α, β -unsaturated groups such as Vinyltrimethoxysilane (VSi), vinyltriethoxysilane, and vinyltris (methoxyethoxy) silane; acrylic esters such as methyl acrylate and ethyl acrylate; methacrylates such as methyl methacrylate and ethyl methacrylate; vinyl esters such as vinyl acetate, vinyl benzoate, and "VeoVA" (trade name, vinyl ester manufactured by shell company); and so on. Among these, the non-fluorine-containing monomer preferably contains 1 or more selected from the group consisting of alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organosilicon compounds having a reactive α, β -unsaturated group.

Among these, the fluorine-containing resin preferably contains a resin having a high fluorination rate, more preferably contains 1 or more resins selected from the group consisting of Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE), and still more preferably contains 1 or more resins selected from the group consisting of PTFE, FEP, and PFA.

Method for granulating fluororesin

The method for granulating the fluorine-containing resin is not particularly limited, and any of a method for granulating by irradiation with radiation (in the present specification, the obtained particles are also referred to as "radiation-irradiated fluorine-containing resin particles"), a method for granulating by a polymerization method (in the present specification, the obtained particles are also referred to as "polymerized fluorine-containing resin particles"), and the like can be used.

The radiation irradiation type fluororesin particles (fluororesin particles obtained by irradiation with radiation) are fluororesin particles obtained by polymerizing radiation and granulating the fluororesin particles at the same time, and the fluororesin particles after polymerization are reduced in weight and micronized by irradiation with radiation. The radiation irradiation type fluorine-containing resin particles also contain a large amount of carboxyl groups because they generate a large amount of carboxylic acids by irradiation with radiation in the air.

The polymerizable fluororesin particles (fluororesin particles obtained by polymerization) mean fluororesin particles which are polymerized and granulated by suspension polymerization, emulsion polymerization, or the like, and are not irradiated with radiation. The polymerizable fluorine-containing resin particles are produced by polymerization in the presence of a basic compound, and therefore contain the basic compound as a residue.

Among these, the fluorine-containing resin particles are preferably polymerizable fluorine-containing resin particles. As described above, the polymerizable fluororesin particles are fluororesin particles that are polymerized and granulated by a suspension polymerization method, an emulsion polymerization method, or the like, and are not irradiated with radiation.

Average particle diameter

The average particle diameter of the fluorine-containing resin particles is not particularly limited, but is preferably 0.1 μm to 4 μm, more preferably 0.1 μm to 2 μm. The fluorine-containing resin particles (particularly PTFE particles and the like) having an average particle diameter of 0.1 to 4 μm tend to contain PFOA in a large amount. Therefore, the fluorine-containing resin particles having an average particle diameter of 0.1 μm or more and 4 μm or less tend to have a particularly low chargeability. However, by controlling the amount of PFOA to the above range, even the fluorine-containing resin particles having an average particle diameter of 0.1 μm or more and 4 μm or less are considered to have improved chargeability. The average particle diameter of the fluorine-containing resin particles is a value measured by the above-mentioned method.

Specific surface area

From the viewpoint of dispersion stability, the specific surface area (BET specific surface area) of the fluorine-containing resin particles is preferably 5m²15m above g²A ratio of 7m or less, more preferably²13m above g²The ratio of the carbon atoms to the carbon atoms is less than g. The specific surface area was measured by a nitrogen substitution method using a BET specific surface area measuring instrument (Flowsoap II2300 manufactured by Shimadzu corporation).

Apparent density

From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles is preferably 0.2g/ml to 0.5g/ml, more preferably 0.3g/ml to 0.45 g/ml. The apparent density is a value measured according to JIS K6891 (1995).

Melting temperature

The melting temperature of the fluorine-containing resin particles is preferably 300 ℃ to 340 ℃ and more preferably 325 ℃ to 335 ℃. The melting temperature is a melting point measured according to JIS K6891 (1995).

(fluorinated dispersant)

The fluorine-containing resin particles may have a dispersant having a fluorine atom (hereinafter also referred to as "fluorine-containing dispersant") attached to the surface thereof. The fluorine-containing dispersant may be 1 kind alone or 2 or more kinds in combination.

Examples of the fluorine-containing dispersant include a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluoroalkyl group (hereinafter also referred to as "fluoroalkyl group-containing polymer"), a fluorine-based surfactant, and the like, and a polymer containing a fluoroalkyl group is preferably contained.

Specific examples of the fluoroalkyl group-containing polymer include homopolymers of fluoroalkyl group-containing (meth) acrylates, random or block copolymers of fluoroalkyl group-containing (meth) acrylates and monomers having no fluorine atom, and the like. In the present specification, the term (meth) acrylate refers to both acrylate and methacrylate.

Examples of the monomer having no fluorine atom include (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, t-butyl (meth) acrylate, n-2-ethoxyethyl (meth) acrylate, n-ethyl (meth) acrylate, n-2-methoxyethyl (meth) acrylate, n-2-ethoxyethyl (meth) acrylate, n-butyl (meth) acrylate, n-2-butyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl (meth) acrylate, n-2-butyl acrylate, n-butyl (meth) acrylate, n-butyl acrylate, n-butyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl acrylate, n-butyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl acrylate, n-butyl acrylate, n-butyl acrylate, n-acrylate, methoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, hydroxyethyl o-phenylphenol (meth) acrylate, o-phenylphenol glycidyl ether (meth) acrylate.

Further, as the fluorinated dispersant other than the above, there may be mentioned a block polymer and a branched polymer disclosed in the specification of U.S. Pat. No. 5637142 and Japanese patent No. 4251662.

The fluoroalkyl group-containing polymer preferably contains a fluoroalkyl group-containing polymer having a structural unit represented by the following general Formula (FA), and more preferably contains a fluoroalkyl group-containing polymer having a structural unit represented by the following general Formula (FA) and a structural unit represented by the following general Formula (FB).

Next, a fluoroalkyl group-containing polymer having a structural unit represented by the following general Formula (FA) and a structural unit represented by the following general Formula (FB) will be described.

In the general Formulae (FA) and (FB), R^F1、R^F2、R^F3And R^F4Each independently represents a hydrogen atom or an alkyl group.

X^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-Or a single bond.

Y^F1Represents an alkylene chain, a halogen-substituted alkylene chain, - (C)_fxH_2fx-1(OH)) -, or a single bond.

Q^F1represents-O-or-NH-.

fl, fm and fn each independently represent an integer of 1 or more.

fp, fq, fr and fs each independently represents an integer of 0 or 1 or more.

ft represents an integer of 1 to 7.

fx represents an integer of 1 or more.

In the general Formulae (FA) and (FB), R is represented^F1、R^F2、R^F3And R^F4The group (2) is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

In the general Formulae (FA) and (FB), as X^F1And Y^F1The alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) of (a) is preferably a linear or branched alkylene chain having 1 to 10 carbon atoms.

Represents Y^F1Of (C)_fxH_2fx-1Fx in (OH)) -preferably represents an integer of 1 to 10.

fp, fq, fr and fs preferably each independently represent 0 or an integer of 1 to 10.

fn is preferably 1 to 60, for example.

In the fluoroalkyl group-containing polymer having a structural unit represented by general Formula (FA) and a structural unit represented by general Formula (FB), the ratio of the structural unit represented by general Formula (FA) to the structural unit represented by general Formula (FB), that is, fl: fm is preferably 1: 9 above 9: 1 or less, more preferably 3: 7 above 7: 3 or less.

The fluoroalkyl group-containing polymer may be a polymer obtained by polymerizing a monomer having a structural unit represented by the general Formula (FC) in addition to the structural unit represented by the general Formula (FA) and the structural unit represented by the general Formula (FB). In this case, the content ratio of the structural unit represented by the general Formula (FC) is preferably 10 in terms of the ratio (fl + fm: fz) to the total of the structural units represented by the general Formulae (FA) and (FB) (i.e., fl + fm): 0 to 7: 3 or less, more preferably 9: 1 to 7: 3 or less.

(FC)

In the general Formula (FC), R^F5And R^F6Each independently represents a hydrogen atom or an alkyl group. fz represents an integer of 1 or more.

In the general Formula (FC), as R^F5And R^F6The group (2) is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

Commercially available products of fluoroalkyl group-containing polymers include, for example, GF300, GF400 (manufactured by east asian synthesis corporation), Surflon (registered trademark) series (manufactured by AGC Seimi Chemical corporation), Ftergent series (manufactured by NOES corporation), PF series (manufactured by north village Chemical corporation), MEGAFACE (registered trademark) series (manufactured by DIC), FC series (manufactured by 3M), and the like.

Weight average molecular weight Mw

The weight average molecular weight Mw of the fluoroalkyl group-containing polymer is preferably 2 to 20 ten thousand, more preferably 5 to 20 ten thousand, from the viewpoint of improving the dispersibility of the fluorine-containing resin particles.

The weight average molecular weight of the fluoroalkyl group-containing polymer was measured by Gel Permeation Chromatography (GPC). The molecular weight measurement by GPC is carried out, for example, by using GPC/HLC-8120 manufactured by Tosoh as a measuring apparatus, a column TSKgel GMHHR-M + TSKgel GMHHR-M (7.8mmI.D.30cm) manufactured by Tosoh, a chloroform solvent, and a molecular weight calibration curve prepared by using a monodisperse polystyrene standard sample.

Content of

The content of the fluorine-containing dispersant is, for example, preferably 0.5 to 10% by mass, more preferably 1 to 7% by mass, based on the fluorine-containing resin particles.

Surface adhesion method of fluorine-containing dispersant

The method for adhering the fluorine-containing dispersant to the surface of the fluorine-containing resin particles is not particularly limited, and examples thereof include the following (1) to (3).

(1) A method for producing a dispersion of fluorine-containing resin particles, which comprises mixing fluorine-containing resin particles and a fluorine-containing dispersant into a dispersion solvent.

(2) A method of mixing fluorine-containing resin particles with a fluorine-containing dispersant using a dry powder mixer to adhere the fluorine-containing dispersant to the fluorine-containing resin particles.

(3) A method in which a fluorine-containing dispersant dissolved in a solvent is dropped while stirring fluorine-containing resin particles, and then the solvent is removed.

Charge transport layer

Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4, 7-trinitrofluorenone; a xanthone-based compound; a benzophenone-based compound; a cyanovinyl compound; electron-transporting compounds such as vinyl compounds. Examples of the charge transport material include hole transport compounds such as triarylamine compounds, biphenylamine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and the like. These charge transport materials may be used alone in 1 kind or in two or more kinds, but are not limited thereto.

Among these compounds, triarylamine-based compounds and biphenylamine-based compounds are preferable charge transport materials from the viewpoint of charge mobility. Among them, as the triarylamine-based compound, a charge transport material represented by the following formula (CT1) (hereinafter, also referred to as "butadiene-based charge transport material") is preferable as an example of the triarylamine-based compound. Further, as the benzidine-based compound, a charge transport material represented by the following general formula (CT2) (hereinafter also referred to as "benzidine-based charge transport material") is preferable.

Butadiene-based charge transport material

The following is a description of the butadiene-based charge transport material. The butadiene-based charge transport material is represented by the following general formula (CT 1).

In the general formula (CT1), R^C11、R^C12、R^C13、R^C14、R^C15And R^C16Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and adjacent 2 substituents may be bonded to each other to form a hydrocarbon ring structure. n and m each independently represent 0, 1 or 2.

In the general formula (CT1), R is^C11、R^C12、R^C13、R^C14、R^C15And R^C16Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

In the general formula (CT1), R is^C11、R^C12、R^C13、R^C14、R^C15And R^C16Examples of the alkyl group include linear or branched alkyl groups having 1 to 20 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

Specific examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-eicosyl group.

Specific examples of the branched alkyl group include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, isoundecyl group, sec-undecyl group, tert-undecyl group, neoundecyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, neododecyl group, isotridecyl group, sec-tridecyl group, tert-tridecyl group, neotridecyl group, isotetradecyl group, sec-tetradecyl group, tert-tetradecyl group, neotetradecyl group, 1-isobutyl-4-ethyloctyl group, isopentadecyl group, sec-pentadecyl group, tert-pentadecyl group, neopentadecyl group, isohexadecyl group, sec-hexadecyl group, and sec-hexadecyl group, Tertiary hexadecyl, neohexadecyl, 1-methylpentadecyl, isoheptadecyl, secondary heptadecyl, tertiary heptadecyl, neoheptadecyl, isooctadecyl, secondary octadecyl, tertiary octadecyl, neooctadecyl, isononadecyl, secondary nonadecyl, tertiary nonadecyl, neononadecyl, 1-methyloctyl, isoeicosyl, secondary eicosyl, tertiary eicosyl, neoeicosyl, and the like.

Among these, the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, or an isopropyl group.

In the general formula (CT1), R is^C11、R^C12、R^C13、R^C14、R^C15And R^C16Examples of the alkoxy group include a linear or branched alkoxy group having 1 to 20 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, a n-propoxy group, a n-butoxy group, a n-pentoxy group, a n-hexoxy group, a n-heptoxy group, a n-octoxy group, a n-nonoxy group, a n-decoxy group, a n-undecyloxy group, a n-dodecoxy group, a n-tridecyloxy group, a n-tetradecyloxy group, a n-pentadecyloxy group, a n-hexadecyloxy group, a n-heptadecyl-oxy group, a n-octadecyl-oxy group, a n-nonadecyl-oxy group, and a n-eicosyl-oxy group.

Specific examples of the branched alkoxy group include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, an isoheptyloxy group, a sec-heptyloxy group, a tert-heptyloxy group, an isooctyloxy group, a sec-octyloxy group, a tert-octyloxy group, an isononyloxy group, a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, a tert-decyloxy group, an isoundecyloxy group, a tert-undecyloxy group, an isododecyloxy group, a sec-dodecyloxy group, a tert-dodecyloxy group, a neododecyloxy group, an isotridecyloxy group, a secondary tridecyloxy group, a tert-tridecyloxy group, a neotridecyloxy group, an isotetradecyloxy group, a sec-tetradecyloxy group, a neotetradecyloxy group, 1-isobutyl-4-ethyloctyloxy, isopentadecyloxy, sec-pentadecyloxy, t-pentadecyloxy, neopentadecyloxy, isohexadecyloxy, sec-hexadecyloxy, t-hexadecyloxy, neohexadecyloxy, 1-methylpentadecyloxy, isoheptadecyloxy, sec-heptadecyloxy, t-heptadecyloxy, neoheptadecyloxy, isooctadecyloxy, sec-octadecyloxy, t-octadecyloxy, neooctadecyloxy, isononadecyloxy, sec-nonadecyloxy, t-nonadecyloxy, neononadecyloxy, 1-methyloctyloxy, isoeicosyloxy, sec-eicosyloxy, t-eicosyloxy, neoeicosyloxy, and the like.

Among these, the alkoxy group is preferably a methoxy group.

In the general formula (CT1), R is^C11、R^C12、R^C13、R^C14、R^C15And R^C16Examples of the aryl group include aryl groups having 6 to 30 (preferably 6 to 20, more preferably 6 to 16) carbon atoms.

Specific examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and a biphenyl group.

Among these, as the aryl group, phenyl and naphthyl are preferable.

In the general formula (CT1), R^C11、R^C12、R^C13、R^C14、R^C15And R^C1The above-mentioned substituents also include groups further having substituents. Examples of the substituent include the atoms and groups exemplified above (for example, a halogen atom, an alkyl group, an alkoxy group, an aryl group, and the like).

In the general formula (CT1), R is^C11、R^C12、R^C13、R^C14、R^C15And R^C16Are adjacent to each other (e.g. R)^C11And R^C12Each other, R^C13And R^C14Each other, R^C15And R^C16The group connecting the substituents in the hydrocarbon ring structure formed by connecting the substituents to each other) includes a single bond, 2 '-methylene, 2' -ethylene, 2 '-1, 2-vinylene and the like, and among them, a single bond and 2, 2' -methylene are preferable.

Specific examples of the hydrocarbon ring structure include a cycloalkane structure, a cycloalkene structure, and a cycloalkane polyene structure.

In the general formula (CT1), n and m are preferably 1.

In the general formula (CT1), R is preferably R from the viewpoint of forming a photosensitive layer (charge transport layer) having high charge transport ability^C11、R^C12、R^C13、R^C14、R^C15And R^C16Represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, m and n represent 1 or 2, more preferably R^C11、R^C12、R^C13、R^C14、R^C15And R^C16Represents a hydrogen atom, and m and n represent 1.

That is, the butadiene-based charge transport material (CT1) is more preferably a charge transport material represented by the following structural formula (CT1A) (an exemplary compound (CT 1-3)).

Specific examples of the butadiene-based charge transport material (CT1) are shown below, but the present invention is not limited thereto. Hereinafter, the following exemplary compound numbers will be referred to as exemplary compounds (CT 1-number). Specifically, for example, the exemplary compound 15 is described as "exemplary compound (CT 1-15)" hereinafter.

No.

m

n

R^C11

R^C12

R^C13

R^C14

R^C15

R^C16

CT1-1

1

4-CH₃

H

CT1-2

2

H

4-CH₃

CT1-3

1

H

CT1-4

2

H

CT1-5

1

4-CH₃

H

CT1-6

0

1

H

CT1-7

0

1

4-CH₃

CT1-8

0

1

4-CH₃

H

4-CH₃

CT1-9

0

1

H

4-CH₃

H

CT1-10

0

1

H

4-CH₃

H

CT1-11

0

1

4-CH₃

H

4-CH₃

H

CT1-12

0

1

4-OCH₃

H

4-OCH₃

H

CT1-13

0

1

H

4-OCH₃

H

CT1-14

0

1

4-OCH₃

H

4-OCH₃

H

4-OCH₃

CT1-15

0

1

3-CH₃

H

3-CH₃

H

3-CH₃

H

CT1-16

1

4-CH₃

CT1-17

1

4-CH₃

H

4-CH₃

CT1-18

1

H

4-CH₃

H

CT1-19

1

H

3-CH³

3-CH₃

H

CT1-20

1

4-CH₃

H

4-CH₃

H

CT1-21

1

4-OCH₃

H

4-OCH₃

H

CT1-22

1

H

4-OCH₃

H

CT1-23

1

4-OCH₃

H

4-OCH₃

H

4-OCH₃

CT1-24

1

3-CH₃

H

3-CH₃

H

3-CH₃

H

In the above exemplary compounds, the abbreviation symbols represent the following meanings. The numbers attached to the substituents above represent the substitution positions on the benzene ring.

·-CH₃: methyl radical

·-OCH₃: methoxy radical

The butadiene-based charge transport material (CT1) may be used alone or in combination of two or more.

Biphenylamine-based charge transport material

As the benzidine-based compound, a benzidine-based charge transport material (CT2) represented by the following general formula (CT2) is preferably used in view of charge mobility.

In particular, from the viewpoint of charge mobility, it is preferable to use a butadiene-based charge transport material (CT1) in combination with a benzidine-based charge transport material (CT2) as the charge transport material. In view of charge transport performance, the mass ratio (the content of the butadiene-based charge transport material (CT 1)/the content of the benzidine-based charge transport material (CT 2)) when the butadiene-based charge transport material (CT1) and the benzidine-based charge transport material (CT2) are used in combination is preferably 1/9 to 5/5, and more preferably 1/9 to 4/6.

The benzidine-based charge transport material will be described below. The benzidine-based charge transport material is represented by the following general formula (CT 2).

In the general formula (CT2), R^C21、R^C22And R^C23Each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, an alkyl group, an alkoxy group, or an aryl group.

In the general formula (CT2), R is^C21、R^C22And R^C23Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

In the general formula (CT2), R is^C21、R^C22And R^C23Examples of the alkyl group include linear or branched alkyl groups having 1 to 10 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

Specific examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

Specific examples of the branched alkyl group include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, and tert-decyl group.

In the general formula (CT2), R is^C21、R^C22And R^C23Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 10 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, a n-propoxy group, a n-butoxy group, a n-pentoxy group, a n-hexoxy group, a n-heptoxy group, a n-octoxy group, a n-nonoxy group, and a n-decoxy group.

Specific examples of the branched alkoxy group include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, an isoheptyloxy group, a sec-heptyloxy group, a tert-heptyloxy group, an isooctyloxy group, a sec-octyloxy group, a tert-octyloxy group, an isononyloxy group, a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, and a tert-decyloxy group.

Among these, the alkoxy group is preferably a methoxy group.

In the general formula (CT2), R is^C21、R^C22And R^C23Examples of the aryl group include aryl groups having 6 to 10 (preferably 6 to 9, and more preferably 6 to 8) carbon atoms. Specific examples of the aryl group include a phenyl group and a naphthyl group. Among these, as the aryl group, a phenyl group is preferable.

In the general formula (CT2), R^C21、R^C22And R^C23The above-mentioned substituents also include groups having further substituents. Examples of the substituent include the atoms and groups exemplified above (for example, a halogen atom, an alkyl group, an alkoxy group, an aryl group, and the like).

In the general formula (CT2), R is particularly preferable from the viewpoint of forming a photosensitive layer (charge transport layer) having high charge transport ability^C21、R^C22And R^C23Each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R is more preferably^C21、R^C22And R^C23Represents a hydrogen atom, R^C22Represents an alkyl group having 1 to 10 carbon atoms (particularly a methyl group).

Specifically, the benzidine-based charge transport material (CT2) is particularly preferably a charge transport material represented by the following structural formula (CT2A) (exemplified compound (CT 2-2)).

Specific examples of the charge transport material represented by the general formula (CT2) are shown below, but the present invention is not limited thereto. In the following, the following exemplary compound numbers are referred to as exemplary compounds (CT 2-No.). Specifically, for example, the exemplary compound 15 is described as "exemplary compound (CT 2-15)" hereinafter.

No	D^C21	R^C22	R^C23
				CT2-1	H	H	H
CT2-2	H	3-CH₃	H
				CT2-3	H	4-CH₃	H
CT2-4	H	3-C₂H₅	H
				CT2-5	H	4-C₂H₅	H
CT2-6	H	3-OCH₃	H
				CT2-7	H	4-OCH₃	H
CT2-8	H	3-OC₂H₅	H
				CT2-9	H	4-OC₂H₅	H
CT2-10	3-CH₃	3-CH₃	H
				CT2-11	4-CH₃	4-CH₃	H
CT2-12	3-C₂H₅	3-C₂H₅	H
				CT2-13	4-C₂H₅	4-C₂H₅	H
CT2-14	H	H	2-CH₃
				CT2-15	H	H	3-CH₃
CT2-16	H	3-CH₃	2-CH₃
				CT2-17	H	3-CH₃	3-CH₃
CT2-18	H	4-CH₃	2-CH₃
				CT2-19	H	4-CH₃	3-CH₃
CT2-20	3-CH₃	3-CH₃	2-CH₃
				CT2-21	3-CH₃	3-CH₃	3-CH₃
CT2-22	4-CH₃	4-CH₃	2-CH₃
				CT2-23	4-CH₃	4-CH₃	3-CH₃

·-CH₃: methyl radical

·-C₂H₅: ethyl radical

·-OCH₃: methoxy radical

·-OC₂H₅: second stepOxy radical

The benzidine-based charge transport material (CT2) may be used alone or in combination of two or more.

Examples of the binder resin used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinylcarbazole, polysilane, and the like. Among these, as the binder resin, a polycarbonate resin or a polyarylate resin is preferable. The binder resin may be used alone or in combination of two or more.

The mixing ratio of the charge transport material to the adhesive resin is preferably 10: 1 to 1: 5 or less.

When a large amount of fluorine-containing resin particles having a carboxyl group are used together with a polycarbonate resin, the dispersibility of the fluorine-containing resin particles tends to be lowered. In particular, when a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB) in which the number of carbonate groups (-OC (═ O) O-) per unit mole is increased is used, the dispersibility of the fluorine-containing resin particles tends to be lowered. Therefore, in the case of using a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB), it is preferable to use a polycarbonate resin containing 10 carboxyl groups per one unit⁶The number of carbon atoms is 0And more than 30 fluorine-containing resin particles.

In the general formulae (PCA) and (PCB), R^P1、R^P2、R^P3And R^P4Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms. X^P1Represents phenylene, biphenylene, naphthylene, alkylene, or cycloalkylene.

In the general formulae (PCA) and (PCB), as R^P1、R^P2、R^P3And R^P4Examples of the alkyl group include linear or branched alkyl groups having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms).

Specific examples of the linear alkyl group include a methyl group, an ethyl group, a n-propyl group, a n-butyl group, a n-pentyl group, and a n-hexyl group.

Specific examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group.

Among these, lower alkyl groups such as methyl and ethyl are preferred as the alkyl group.

In the general formulae (PCA) and (PCB), as R^P1、R^P2、R^P3And R^P4Examples of the cycloalkyl group include cyclopentyl, cyclohexyl and cycloheptyl.

In the general formulae (PCA) and (PCB), as R^P1、R^P2、R^P3And R^P4Examples of the aryl group include phenyl, naphthyl and biphenyl.

In the general formulae (PCA) and (PCB), as X^P1Examples of the alkylene group include a linear or branched alkylene group having 1 to 12 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms).

Specific examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-undecylene group, and an n-dodecylene group.

Specific examples of the branched alkylene group include isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, neopentylene, tert-pentylene, isohexylene, sec-hexylene, tert-hexylene, isoheptylene, sec-heptylene, tert-hexylene, isooctylene, sec-octylene, tert-octylene, isononyl, sec-nonylene, tert-nonylene, isodecylene, sec-decylene, tert-decylene, isoundecylene, sec-undecylene, tert-undecylene, neoundecylene, isododecylene, sec-dodecylene, tert-dodecylene, neododecylene and the like.

Among these, lower alkyl groups such as methylene, ethylene and butylene are preferable as the alkylene group.

In the general formulae (PCA) and (PCB), as X^P1Examples of the cycloalkylene group include cycloalkylene groups having 3 to 12 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 8 carbon atoms).

Specific examples of the cycloalkylene group include cyclopropylene group, cyclopentylene group, cyclohexylene group, cyclooctylene group, cyclododecylene group and the like.

Among these, as the cycloalkylene group, a cyclohexylene group is preferable.

In the general formulae (PCA) and (PCB), R is^P1、R^P2、R^P3、R^P4And X^P1The above-mentioned substituents also include groups having further substituents. Examples of the substituent include a halogen atom (e.g., a fluorine atom and a chlorine atom), an alkyl group (e.g., an alkyl group having 1 to 6 carbon atoms), a cycloalkyl group (e.g., a cycloalkyl group having 5 to 7 carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 to 4 carbon atoms), an aryl group (e.g., a phenyl group, a naphthyl group, a biphenyl group, etc.), and the like.

In the general formula (PCA) in which,R^P1and R^P2Each independently preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R^P1And R^P2More preferably represents a hydrogen atom.

In the general formula (PCB), R^P3And R^P4Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X^P1Preferably represents alkylene or cycloalkylene.

Specific examples of the BP polycarbonate resin include, but are not limited to, the following. In the exemplified compounds, pm and pn represent copolymerization ratios.

(PC-1)

(PC-2)

(PC-3)

Here, the content (copolymerization ratio) of the structural unit represented by the general formula (PCA) in the P polycarbonate resin may be in the range of 5 mol% to 95 mol% with respect to the total structural units constituting the polycarbonate resin, and is preferably in the range of 5 mol% to 50 mol% from the viewpoint of suppressing the density unevenness of the granular image, and more preferably in the range of 15 mol% to 30 mol%.

Specifically, in the above exemplified compounds of BP polycarbonate resin, pm and pn represent copolymerization ratios (molar ratios), pm: pn 95: 5 to 5: range of 95, 50: 50 to 5: the range of 95 is more preferably 15: 85 to 30: 70, or less.

other known additives may also be included in the charge transport layer.

Surface protective layer

The surface protective layer is provided on the photosensitive layer as needed.

The surface protective layer is provided, for example, for the purpose of preventing chemical changes of the photosensitive layer at the time of charging or further improving the mechanical strength of the photosensitive layer. Therefore, a layer composed of a cured film (crosslinked film) may be applied as the surface protective layer.

Examples of the surface protective layer formed of a cured film include the following layers (1) and (2).

(1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule (i.e., a layer containing a polymer or a crosslinked body of the reactive group-containing charge transport material)

(2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge-transporting skeleton but having a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked body of the reactive group-containing non-charge transport material)

Other known additives may be included in the surface protective layer.

The film thickness of the surface protective layer is set in a range of preferably 1 μm to 20 μm, and more preferably 2 μm to 10 μm, for example.

Image forming apparatus and process cartridge

The descriptions of the image forming apparatus and the process cartridge are the same as those of embodiment 1, and therefore, are omitted. Note that the charging device, the exposure device, the developing device, the transfer device, and the intermediate transfer member of the image forming apparatus are also the same as those of embodiment 1, and therefore, description thereof is omitted.

Cleaning device

The cleaning device 13 supported by the process cartridge uses a cleaning blade type device provided with a cleaning blade 131.

Examples

The following describes examples of embodiment 1, but the present invention is not limited to these examples. In the following description, "part" and "%" are based on mass unless otherwise specified.

< production of fluorine-containing resin pellets >

(production of fluorine-containing resin particles (1))

The fluorine-containing resin particles (1) were produced as follows.

3 liters of deionized water, 3.0g of ammonium perfluorooctanoate, and 110g of paraffin wax (manufactured by Nippon Petroleum Co., Ltd.) as an emulsion stabilizer were charged into an autoclave, the inside of the system was replaced 3 times with nitrogen gas, the inside of the system was replaced 2 times with TFE (tetrafluoroethylene), oxygen was removed, the internal pressure was set to 1.0MPa with TFE, and the internal temperature was maintained at 70 ℃ while stirring at 250 rpm. Then, 150cc of ethane as a chain transfer agent at normal pressure and 20ml of an aqueous solution containing 300mg of ammonium persulfate dissolved therein as a polymerization initiator were charged into the system to initiate a reaction. During the reaction, TFE was continuously supplied so that the temperature in the system was maintained at 70 ℃ and the internal pressure of the autoclave was always maintained at 1.0. + -. 0.05 MPa. After the initiator was added, the reaction was terminated by stopping the supply and stirring of TFE when TFE consumed in the reaction reached 1000 g. Thereafter, the particles were separated by centrifugal separation, and 400 parts by mass of methanol was further collected and washed with a stirrer at 250rpm for 10 minutes while being irradiated with ultrasonic waves, and the supernatant was filtered off. After repeating this operation 3 times, the filtrate was dried at 60 ℃ for 17 hours under reduced pressure.

Through the above steps, the fluorine-containing resin particles (1) are produced.

< example 1>

(production of photoreceptor)

The obtained fluorine-containing resin particles were used to produce a photoreceptor as follows.

Zinc oxide (average particle diameter 70 nm: manufactured by TAYCA corporation: specific surface area value 15 m)²100 parts/g) and 500 parts of tetrahydrofuran were mixed with stirring, and a silane coupling agent (KBE 503: manufactured by shin-Etsu chemical industries Co., Ltd.) 1.4 parts, and stirred for 2 hours. Then, the toluene was distilled off by distillation under reduced pressure, and the mixture was calcined at 120 ℃ for 3 hours to obtain silane coupling agent surface-treated zinc oxide.

110 parts of the zinc oxide subjected to the surface treatment and 500 parts of tetrahydrofuran were mixed with stirring, and a solution obtained by dissolving 0.6 part of alizarin in 50 parts of tetrahydrofuran was added thereto and stirred at 50 ℃ for 5 hours. Thereafter, alizarin-added zinc oxide was filtered off by reduced pressure filtration and further dried under reduced pressure at 60 ℃ to obtain alizarin-attached zinc oxide.

60 parts of the alizarin-added zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, Sumidur3175, Sumitomo-Bayer Urethane co., ltd.), 15 parts of a butyral resin (S-LECBM-1, manufactured by hydrochemical industries, inc.) and 85 parts of methyl ethyl ketone were mixed to obtain a mixed solution. This mixed solution 38 parts and methyl ethyl ketone 25 parts were mixed and used

The glass beads were dispersed for 2 hours by a sand mill to obtain a dispersion.

To the obtained dispersion, 0.005 part of dioctyltin dilaurate and 30 parts of silicone resin particles (TOSPEARL 145, Momentive Performance Materials Japan contract) were added as catalysts to obtain a coating liquid for an undercoat layer. The coating liquid was applied to a cylindrical aluminum substrate by dip coating, and dried and cured at 170 ℃ for 30 minutes to obtain an undercoat layer having a thickness of 24 μm.

Next, 1 part of hydroxygallium phthalocyanine (which has strong diffraction peaks at positions having bragg angles (2 θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 °, and 28.3 ° in the X-ray diffraction spectrum) was mixed with 1 part of polyvinyl butyral (S-LECBM-5, manufactured by water-logging chemical industries) and 80 parts of n-butyl acetate, and the mixture was subjected to a dispersion treatment with glass beads for 1 hour by means of a paint shaker, thereby preparing a coating liquid for a charge-generating layer. The obtained coating liquid was dip-coated on a conductive substrate having an undercoat layer formed thereon, and dried by heating at 130 ℃ for 10 minutes to form a charge generation layer having a film thickness of 0.15 μm.

45 parts of a benzidine compound represented by the following formula (CTM1) as a charge transport material, 55 parts of a polymer compound (viscosity average molecular weight: 40,000) having a repeating unit represented by the following formula (PCZ1) as a binder resin, and 350 parts of toluene and 150 parts of tetrahydrofuran were dissolved, 8.0 parts of the fluorine-containing resin particles (1) and 0.4 parts of a fluorine-containing graft polymer (product name: GF400, manufactured by east asian synthesis) were added, and the mixture was treated 5 times with a high-pressure homogenizer to prepare a coating liquid for a charge transport layer.

The obtained coating liquid was applied onto the charge generating layer by dip coating, and the charge transport layer was formed to a film thickness of 31 μm by blowing air at a wind speed of 1.5m/s and heating at 120 ℃ for 30 minutes.

Through the above steps, a photoreceptor was produced.

(production of Process Cartridge)

The photoreceptor thus produced was mounted in a process cartridge provided with a cleaning member of an image forming apparatus (docupint CP500d, manufactured by fuji xerox) to obtain a process cartridge. In addition, process cartridges were produced in which the contact pressure of 5 cleaning members in total against the photoreceptor was as shown in table 2.

< examples 2 to 18 and comparative examples 1 to 4>

A photoreceptor and a process cartridge were produced in the same manner as in example 1 except that the kind, the addition amount, and the occupied area of the fluorine-containing resin particles, the addition amount of the fluorine-containing graft polymer, the heating condition of the coating liquid for the charge transport layer, and the contact pressure of the cleaning member with respect to the photoreceptor were changed as described in tables 2 and 3. Only 1 cartridge was produced in each example.

< evaluation >

(evaluation of image quality)

The process cartridges obtained in each example were individually packaged (shipped) and set in a vibration tester (model G-9223LS manufactured by shakedown corporation, ltd.) and all vibration conditions (i) to (iii) shown in table 1 below were applied (in table 1,. indicates that the frequency was changed from 100Hz to 3Hz at a scanning ratio of 0.3 Hz/sec after the scanning ratio was changed from 3Hz to 100Hz at a scanning ratio of 0.3 Hz/sec). The process cartridge was attached to an image forming apparatus (docupint CP500d, manufactured by fuji xerox corporation), a halftone image of 30% density was output onto a4 paper (P paper, manufactured by fuji xerox) in an environment of 22 ℃ and 55% RH to perform image formation, and the images formed on the 1 st and 15 th sheets were visually evaluated. After that, after being left for 24 hours, the image formed on the 1 st sheet was evaluated by visual observation. The criteria for determination are as follows.

-criterion-

A: no streaks were produced.

B: faint stripes were visible at fixation.

C: the presence of a striped image was weakly confirmed in the halftone image, but there was no practical problem.

D: in the halftone image, the presence of a striped image was confirmed, but was not detected in the text image.

E: the presence of a striped image can be clearly recognized in a halftone image, and the presence of stripes can be weakly recognized even in a text image.

F: the presence of streaks is clearly evident in halftone images and text images.

(evaluation of residual potential)

The photoreceptor obtained in each example was rotated at 100rpm, charged to-700V by a scorotron charger in this state, and then irradiated with a semiconductor laser having a wavelength of 780nm for 0.05 second to give a charge of 2.0mJ/m²To discharge it. Then, the photoreceptor 0.1 second after the discharge was irradiated with 20mJ/m²The red LED light of (1) is discharged. Then, the potential V of the surface of the photoreceptor after 100msec from the charge removal was measured and used as the value of the residual potential.

The residual potential was evaluated according to the following criteria.

A: -50V or more

B: less than-50V and more than-100V

C: less than-100V

The descriptions in table 2 and table 3 are explained below.

The "heating conditions" mean coating heating conditions of the coating liquid for a charge transport layer at the time of formation of the charge transport layer.

The "fluorine atom concentration ratio" represents a multiple of the fluorine atom concentration measured at the surface of the charge transport layer with respect to the fluorine atom concentration measured at a depth of 1 μm from the surface of the above-mentioned charge transport layer.

The "charge transport material concentration ratio" means a multiple of the concentration of the charge transport material measured at the surface of the charge transport layer with respect to the concentration of the charge transport material measured at the center of the thickness of the charge transport layer described above.

From the above results, it is understood that the photoreceptor of the present embodiment can suppress the generation of stripe-like image defects and residual potential caused by rubbing of the photoreceptor and the contact member thereof due to vibration.

Hereinafter, examples of embodiment 2 will be described in detail with reference to examples, but the present embodiment is not limited to these examples at all. In the following description, "part" and "%" are based on mass unless otherwise specified.

Production of electrophotographic photoreceptor

[ example 19]

(formation of undercoat layer)

100 parts by mass of zinc oxide particles (trade name: MZ 300, manufactured by TAYCA corporation, volume average primary particle diameter 35nm), 10 parts by mass of a 10% by mass toluene solution of N-2- (aminoethyl) -3-aminopropyltriethoxysilane as a silane coupling agent, and 200 parts by mass toluene were mixed and stirred, and then refluxed for 2 hours. Thereafter, toluene was distilled off under reduced pressure at 10mmHg, and the mixture was baked at 135 ℃ for 2 hours to perform surface treatment of zinc oxide with a silane coupling agent.

33 parts by mass of the surface-treated zinc oxide particles, 6 parts by mass of a blocked isocyanate (trade name: Sumidur3175, Sumitomo-Bayer Urethane Co., Ltd., manufactured by Ltd.), 1 part by mass of a compound represented by the following general formula (AK-1) and 25 parts by mass of methyl ethyl ketone were mixed for 30 minutes, and then 5 parts by mass of a butyral resin (trade name: S-LECBM-1, manufactured by waterlogging chemical industries, Ltd.), 3 parts by mass of silicone spheres (trade name: TOSPEARL 120, manufactured by Momentive Performance Materials, Ltd.) and 0.01 part by mass of Toray Dow Corning silicone oil (trade name: SH29PA, manufactured by Dow Corning Co., Ltd.) as a leveling agent were added, and dispersion was carried out for 1.8 hours (that is, dispersion time was made to 1.8 hours) by a sand mill to obtain a coating liquid for forming an undercoat layer.

Further, the obtained coating liquid for forming an undercoat layer was applied onto an aluminum substrate (conductive substrate) having a diameter of 47mm, a length of 357mm and a thickness of 1mm by a dip coating method, and dried and cured at 180 ℃ for 30 minutes to obtain an undercoat layer having a thickness of 25 μm.

(formation of Charge generating layer)

A hydroxygallium phthalocyanine pigment as a charge generation material, a V-type hydroxygallium phthalocyanine pigment having diffraction peaks at positions having a bragg angle (2 theta + -0.2 DEG) of at least 7.3 DEG, 16.0 DEG, 24.9 DEG and 28.0 DEG in an X-ray diffraction spectrum using Cuk alpha characteristic X-rays (in a wavelength region of 600nm to 900nm inclusive)The maximum peak wavelength in the light absorption spectrum was 820nm, the average particle diameter was 0.12 μm, the maximum particle diameter was 0.2 μm, and the specific surface area was 60m²And/g) ", a vinyl chloride-vinyl acetate copolymer resin as an adhesive resin (trade name: VMCH, manufactured by NUC Co., Ltd.), and n-butyl acetate at a filling rate of 50% with

The glass beads were put together in a glass bottle having a capacity of 100mL, and dispersed for 2.5 hours by a paint shaker to obtain a coating liquid for a charge generating layer. In the mixture of the hydroxygallium phthalocyanine pigment and the vinyl chloride-vinyl acetate copolymer resin, the content of the hydroxygallium phthalocyanine pigment was 55.0 vol%, and the solid content of the dispersion was 6.0 mass%. Assuming that the specific gravity of the hydroxygallium phthalocyanine pigment is 1.606g/cm³The specific gravity of the vinyl chloride-vinyl acetate copolymer resin was 1.35g/cm³And the content ratio is calculated.

The obtained coating liquid for forming a charge generation layer was dip-coated on an undercoat layer, and dried at 100 ℃ for 5 minutes to form a charge generation layer having a film thickness of 0.20 μm.

(formation of Charge transport layer)

8.0 parts by mass of an exemplary compound (CT1-1) as a hole transport material represented by the general formula (1) and 32.0 parts by mass of a diphenylamine-based charge transport material (CT2-1) as charge transport materials, 60.0 parts by mass of a BP polycarbonate resin (pm: pn. 25: 75, viscosity average molecular weight: 5 ten thousand) as a binder resin represented by the general formula (PC-1), 8 parts by mass of Polytetrafluoroethylene (PTFE) as fluorine-containing resin particles, 0.2 parts by mass of "400 (manufactured by Toyo chemical Co., Ltd., surfactant containing at least a fluoroalkyl group-containing methacrylate as a polymerization component)" as a fluorine-containing dispersant, and 3.2 parts by mass of a hindered phenol-based antioxidant (molecular weight 775) as an antioxidant (8.0% by mass relative to 100% by mass of the total amount of charge transport materials) as an antioxidant were added to 340.0 parts by mass of tetrahydrofuran and dissolved, the resultant was treated 10 times with a high-pressure homogenizer to obtain a coating liquid for forming a charge transport layer. The obtained coating liquid for forming a charge transport layer was dip-coated on the charge generating layer.

In the case of dip coating, a charge transport layer having a thickness of 40 μm was formed as an electrophotographic photoreceptor by drying at 150 ℃ for 40 minutes, assuming that the temperature of the coating liquid was 31 ℃, the rising speed of the coating liquid was 800 mm/minute, the rising speed of the material to be coated (substrate formed to the charge generation layer) was 300 mm/minute, and the relative speed difference between the coating liquid and the material to be coated was 500 mm/minute.

The number of carboxyl groups in the fluorine-containing resin particles measured by the above-mentioned method and the amount of triethylamine (boiling point: 89 ℃ C.) as a basic compound are shown in Table 4.

Examples 20 to 29 and comparative example 7

Electrophotographic photoreceptors of respective examples were produced in the same manner as in example 19 except that the types and amounts of the fluorine-containing resin particles, the state of the outermost surface layer (N1 to N3, N2/N1, S1, S2, S2/S1, N3/N1, D1, D2, and D2/D1), the relative velocity difference between the coating liquid for forming a charge transport layer and the material to be coated (matrix formed to the charge generation layer), the types and amounts of the charge transport materials, and the like in example 19 were changed to the specifications shown in tables 4 and 5. In the case where two or more charge transport materials are used, the amount of the charge transport material shown in table 4 is the sum of the amounts of the charge transport materials.

[ comparative examples 5 to 6]

Electrophotographic photoreceptors of respective examples were produced in the same manner as in example 19 except that the type and amount of the fluorine-containing resin particles, the state of the outermost surface layer (N1 to N3, N2/N1, S1, S2, S2/S1, N3/N1, D1, D2, and D2/D1), the number of treatments in the high-pressure homogenizer, the type and amount of the charge transport material, and the like were changed to the specifications shown in tables 4 and 5 in the formation of the charge transport layer in example 19 at a coating liquid temperature of 15 ℃. In the case where two or more charge transport materials are used, the amount of the charge transport material shown in table 4 is the sum of the amounts of the charge transport materials.

Evaluation of sensitivity

The evaluation of sensitivity in the electrophotographic photoreceptor of each example was performed as a half exposure amount when the electrophotographic photoreceptor was charged to + 800V. Specifically, the electrophotographic photoreceptor of each example was charged to +800V in an environment of 20 ℃ C/40% relative humidity using an electrostatic transfer paper test apparatus (Electrostatic Analyzer EPA-8100, manufactured by Kayokoku Kogyo Co., Ltd.). Then, the light of the tungsten lamp was changed to 800nm monochromatic light by a monochromator at a dose of 1. mu.W/cm²The light quantity is adjusted to irradiate the surface of the electrophotographic photoreceptor. Then, the surface potential vo (V) of the electrophotographic photoreceptor immediately after charging was measured for half-exposure (μ J/cm) after the exposure to light²). The obtained values of the half-subtracted amount are classified according to the following criteria. The results are shown in Table 5. If the sensitivity is lowered, the image quality is lowered, and image defects are caused.

G1: the half-reduction exposure amount was 0.10. mu.J/cm²The following.

G2: the half-exposure dose exceeds 0.10 mu J/cm²And is 0.13. mu.J/cm²The following.

G3: the half-exposure dose exceeds 0.13 muJ/cm²And is 0.15. mu.J/cm²The following.

G4: the half-exposure dose exceeds 0.15 mu J/cm²And is 0.18. mu.J/cm²The following.

G5: the half-exposure dose exceeds 0.18 mu J/cm²。

Evaluation of abrasion resistance

The electrophotographic photoreceptor of each example was mounted on a black process cartridge of a color copier, DocuCentre-V C7776, manufactured by fuji schle corporation. Then, a running test was performed to output 100,000 (100kPV) halftone images (i.e., image density 50%) under an environment of 20 ℃ temperature and 40% humidity, and then the amount of wear of the outermost surface of the electrophotographic photoreceptor was measured from the difference between the film thickness measured before and after the running using an eddy current film thickness meter. The results are shown in Table 5.

Evaluation of the number of point-like image defects-

When the carbon fibers penetrated through the respective layers and reached the conductive substrate, a current was passed through the layers to generate a dot-like image defect, and evaluation was performed to suppress generation of a leakage current by utilizing this phenomenon.

The electrophotographic photoreceptor of each example was attached to the black color of DocuCentre-V C7776. Then, a developer containing 10mg (0.1 mass%) of carbon fibers (MLD-30, manufactured by toyo corporation) was mixed with the amount of the developer, and a black image having an image density of 15% was continuously output from a4 white paper. The number of dot-like image defects on the 10 th sheet was visually counted, and the results are shown in table 5.

Evaluation of chargeability-

The charging properties of the electrophotographic photoreceptors of the respective examples were evaluated as follows.

The surface potential after charging was set at-700V by an image forming apparatus for evaluation, and 70,000 full-surface halftone images with an image density of 30% were output on A4 paper in a high-temperature and high-humidity environment (environment at a temperature of 28 ℃ and a humidity of 85% RH). Then, the surface potential was measured by a surface potential meter, and the evaluation was performed according to the following evaluation criteria.

G1: surface potential of-700V or more and less than-690V

G2: surface potential of-690V or more and less than-675V

G3: surface potential of-675V or more and less than-660V (level having no problem in practical use)

G4: surface potential of-660V or more and less than-640V

G5: surface potential of-640V or more

As shown in table 5, the electrophotographic photoreceptors of the examples were found to be superior in sensitivity and wear resistance to those of the comparative examples. In addition, it can be seen that: the electrophotographic photoreceptor of the example can suppress the occurrence of leakage current caused when needle-like foreign matter such as carbon fibers is mixed into the developer, as compared with the electrophotographic photoreceptor of the comparative example.

Description of the symbols

1,101 primer layer

2,102 charge generation layer

3,103 Charge transport layer

4,104 conductive substrate

7A,7,107A,107B electrophotographic photoreceptor

8 charging device

9 Exposure device

11 developing device

13 cleaning device

14 lubricant

40 transfer device

50 intermediate transfer body

100 image forming apparatus

120 image forming apparatus

131 cleaning blade

132 fibrous Member (roll)

133 fibrous component (Flat brush shape)

300 processing box

105 photosensitive layer

106 a surface protection layer.

Claims

1. An electrophotographic photoreceptor having a conductive substrate and a photosensitive layer,

the outermost surface layer contains fluorine-containing resin particles,

(1) the fluorine atom concentration at the surface of the outermost surface layer is 1.5 times or more and 5.0 times or less the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or,

(2) a ratio N2/N1 of a number density N1 of the aggregate of the fluorine-containing resin particles in a first region from a surface of the outermost surface layer to 1/2 of a layer thickness to a number density N2 of the aggregate of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to a bottom surface of the outermost surface layer is less than 0.95,

the ratio S2/S1 of the area ratio S1 of the fluorine-containing resin particles in a first region from the surface of the outermost surface layer to 1/2 of the layer thickness to the area ratio S2 of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to the bottom surface of the outermost surface layer is in the range of 1 + -0.1.

2. The electrophotographic photoreceptor according to claim 1, wherein the fluorine-containing resin particles occupy an area of 0.33% or more and 1.1% or less on the surface of the outermost surface layer.

3. The electrophotographic photoreceptor according to claim 2, wherein the fluorine-containing resin particles occupy an area of 0.36% or more and 0.95% or less on the surface of the outermost surface layer.

4. The electrophotographic photoreceptor according to any one of claim 1 to claim 3, wherein the photosensitive layer has a charge generating layer and a charge transporting layer,

the outermost surface layer is the charge transport layer,

the concentration of the charge transport material at the surface of the charge transport layer is 0.4 times or more and 0.6 times or less the concentration of the charge transport material at the center of the thickness of the charge transport layer.

5. The electrophotographic photoreceptor according to claim 4, wherein the concentration of the charge transport material at the surface of the charge transport layer is 0.45 times or more and 0.56 times or less the concentration of the charge transport material at the center of the thickness of the charge transport layer.

6. The electrophotographic photoreceptor according to claim 1, wherein the ratio N2/N1 is 0.1 or more and 0.8 or less.

7. The electrophotographic photoreceptor according to claim 1 or claim 6, wherein a ratio N3/N1 of a number density N1 of the aggregates of the fluorine-containing resin particles in a first region from a surface to 1/2 of a layer thickness of the outermost surface layer to a number density N3 of the aggregates of the fluorine-containing resin particles in a third region from 9/10 of the layer thickness from the surface of the outermost surface layer to a bottom surface of the outermost surface layer is 0.9 or less.

8. The electrophotographic photoreceptor according to claim 7, wherein the ratio N3/N1 is 0.7 or less.

9. The electrophotographic photoreceptor according to claim 1 or any one of claims 6 to 8, wherein a ratio D2/D1 between an average diameter D1 of the aggregate of the fluorine-containing resin particles in a first region from a surface of the outermost surface layer to 1/2 of a layer thickness and an average diameter D2 of the aggregate of the fluorine-containing resin particles in a second region from 1/2 of the layer thickness to a bottom surface of the outermost surface layer is 2 or more.

10. The electrophotographic photoreceptor according to claim 9, wherein the ratio D2/D1 is 3 or more and 30 or less.

11. The electrophotographic photoreceptor according to claim 1 or any one of claims 6 to 10, wherein the number density N1 of the aggregates of the fluorine-containing resin particles in a first region from the surface to 1/2 in the layer thickness of the outermost surface layer is 5 particles/100 μm²50 pieces/100 mu m²The following.

12. The electrophotographic photoreceptor according to claim 1 or any one of claims 6 to 11, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 per 10 of the fluorine-containing resin particles⁶The number of carbon atoms is 0 to 30, and the amount of the basic compound in the fluorine-containing resin particles is 0ppm to 3 ppm.

13. The electrophotographic photoreceptor according to claim 12, wherein the number of carboxyl groups is per unit10⁶The number of carbon atoms is 0 to 20, and the amount of the basic compound is 0ppm to 3 ppm.

14. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 13,

15. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 5, which is configured to be attached to and detached from an image forming apparatus,

the process cartridge includes a cleaning member configured to contact the electrophotographic photoreceptor to perform cleaning,

16. An image forming apparatus includes:

an electrophotographic photoreceptor according to any one of claims 1 to 13;

17. An image forming apparatus includes:

an electrophotographic photoreceptor according to any one of claims 1 to 5;

a transfer mechanism configured to transfer the toner image to a surface of a recording medium; and